Ppt on chromosomes and genes activities

The Chromosomal Basis of Inheritance. Chromosomal Theory of Inheritance Genes are physically located at loci on chromosomes Additionally, it is chromosomes.

recombination frequencies Cytogenic map: a genetic map based on staining genes and observing them under the microscope X-Inactivation In females, 1 X chromosome in each cell is randomly inactivated and becomes a Barr body Genomic Imprinting Most times the expression of/ the allele is silenced in the sperm or egg, the trait is only active in one gamete (mom’s or dad’s) Mostly occurs in developmental genes Individuals heterozygous for a disease on an imprinted allele show different phenotypes depending on/

Biology Sylvia S. Mader Michael Windelspecht Chapter 13 Regulation of Gene Expression Lecture Outline Copyright © The McGraw-Hill Companies, Inc. Permission.

required for reproduction or display. When the repressor binds to the operator, transcription is prevented. active repressor structural genes regulator gene promoteroperator The trp Operon 7 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction/tortoiseshell cats have patches of orange and black. One X chromosome is inactivated in each cell. Which one is by chance. Females have two X chromosomes. active X chromosome inactive X active X chromosome allele for orange color allele for/

Chromosomes Dr. R. Siva VIT University, INDIA rsiva77in@rediffmail.com.

proteins, separated by size In addition, chromatin contains an approximately equal mass of a wide variety of non-histone chromosomal proteins. There are more than a thousand different types of these proteins, which are involved in a range of activities, including DNA replication and gene expression. The DNA of prokaryotes is similarly associated with proteins, some of which presumably function as histones do, packing/

Eukaryotic chromosomes

commitment Specific genes activated All other genes inactivated Active genes maintain activity Inactive genes remain silent Active genes maintain activity Inactive genes remain silent Transcription activator +++ --- Repressor proteins --- +++ Epigenetics and epigenetic regulation Heritable changes in gene expression that do not involve changes in DNA sequences Genes contain coding regions and promoters . examples: Developmentally regulated / tissue specific gene expression X chromosome dosage compensation/

Chapter 15 Chromosomal basis for inheritance.

orange fur Early embryo: Allele for black fur Cell division and X chromosome inactivation Two cell populations in adult cat: Active X Inactive X Active X Black fur Orange fur Figure 15.8 X inactivation and the tortoiseshell cat Sex-linked Mom passes gene on the X-chromosome to the son Males have one X-chromosome Recessive gene is expressed Recessive alleles on the X are present No counter/

The following is a map of four genes on a chromosome:

Chapter 15~ The Chromosomal Basis of Inheritance The Chromosomal Theory of Inheritance Genes have specific loci on chromosomes and chromosomes undergo segregation and independent assortment Chromosomal Linkage XX (female) vs. XY (male) Morgan Drosophilia melanogaster XX (female) vs. XY (male) Sex-linkage: genes located on a sex chromosome Linked genes: genes located on the same chromosome that tend to be inherited together Classes of chromosomes autosomal chromosomes sex chromosomes Discovery of sex linkage/

Copyright Pearson Prentice Hall

Pearson Prentice Hall 14–2 Colorblindness is much more common in males than in females because the recessive gene on the male’s single X chromosome is expressed. genes on the Y chromosome make genes on the X chromosome more active. females cannot be colorblind. colorblindness is dominant in males and recessive in females. Copyright Pearson Prentice Hall Copyright Pearson Prentice Hall 14–2 The presence of a/

What are chromosomes? Genetic materials found inside the nucleus of a cell Made up of DNA & protein Appear as very thin & thread-like structures called.

chromosome gene controlling skin colour gene controlling tongue rolling gene controlling eye colour gene controlling blood group DNA is responsible for telling the cell to make the right type of protein & control the metabolic activities of the cells Chromosomes/  Separation of chromatids of each chromosome  4 daughter cells with half of the chromosome number of the parent cell are formed Occurrence of meiosis  Plants: anthers and ovules  Mammals: testes and ovaries Comparison between Mitosis & Meiosis /

Human Heredity. Human Chromosomes Humans have 46 total chromosomes Two Categories –Autosomes- first 22 pairs –Sex Chromosomes- 23rd pair, determine sex.

) X and Y Males- XY Females- XX Punnett Square of Gender Karyotype Picture of chromosomes paired up with it’s homologous chromosome –Commonly used for genetic testing Taken during mitosis when chromosomes are visible Dye added to show banding of genes Karyotype Activity Utah Website Types of Disorders Major Categories –Chromosomal –Single Allele (single gene) Chromosomal Disorders- gaining or losing a piece/entire chromosome –Gaining= 47 chromosomes –Losing= 45 chromosomes Why Chromosomal Disorders/

CHAPTER 8 The Cellular Basis of Reproduction and Inheritance Sexual reproduction mitosis asexual reproduction meiosis.

Genes grouped into chromosomes (long thread-like structures) Cell duplicates chromosomes as well as genes Mitosis occurs Duplicated chromosomes are evenly distributed into 2 daughter nuclei cytokinesis Sect 8.3 Chromosomes Consists of a long DNA molecule (represents thousands of genes) Also consists of proteins (structure, helps control gene activity/ & coordinates major events in the cell cycle. Major checkpoints in G 1, G 2, and M: - G 1 checkpoint seems to be most critical in many cells (gives go-ahead/

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chapter 15 Overview: Locating Genes on Chromosomes Genes – Are located on chromosomes.

, Inc. publishing as Benjamin Cummings If a female is heterozygous for a particular gene located on the X chromosome – She will be a mosaic for that character Two cell populations in adult cat: Active X Orange fur Inactive X Early embryo: X chromosomes Allele for black fur Cell division and X chromosome inactivation Active X Black fur Inactive X Figure 15.11 Copyright © 2005 Pearson Education, Inc/

1 Eukaryotic chromosomes BacterialEukaryotic DNA is in a nucleoid bodyDNA is in chromosomes There is one large DNA moleculeThere are many molecules CircularLinear.

residues) that are not methylated and are bound by specific transcription activators. examples: Developmentally regulated / tissue specific gene expression X chromosome dosage compensation Gene Imprinting Position effect variegation (PEV) Enhancer Promoter 13 Cell specific Activation HNF3 Liver gene1 Liver gene2 Brain gene 1 Brain gene 2 NZF2 Different Enhancers bind different tissue and cell specific transcription activator proteins and this enables specific gene activation in specific cells Liver gene1/

Chapter 15 The Chromosomal Basis of Inheritance. Mendelian inheritance has its physical basis in the behavior of chromosomes during meiosis.

mammalian cell needs only one active X chromosome. In females, one of the two X’s is inactivated Chapter 15 The Chromosomal Basis of Inheritance Genomic Imprinting Chapter 15 The Chromosomal Basis of Inheritance Genomic Imprinting Individual genes may also be inactivated. Often this is done preferentially to the maternal or to the paternal copy of the gene. REPRODUCTIVE COMPETITION BETWEEN MALES AND FEMALESDAD MOMMOMMOM KID KIDKID/

Cell Reproduction  Chromosomes  Cell Division  Meiotic Cell Cycle.

” & “Y”  XX = female  XY = male Autosomes (22 pairs = 44 in humans)Autosomes (22 pairs = 44 in humans)  Carry genes for most characters Homologous Chromosomes Karyotype – displays homologuesKaryotype – displays homologues Homologous ChromosomesHomologous Chromosomeschromosome pairs of the same length, centromere position, and staining pattern that posses genes for the same characters  one homologue is inherited from the organism’s father  one homologue is inherited from the organism/

Chromosomes Dr. R. Siva VIT University, INDIA

mass of a wide variety of non-histone chromosomal proteins. There are more than a thousand different types of these proteins, which are involved in a range of activities, including DNA replication and gene expression. There are more than a thousand different types of these proteins, which are involved in a range of activities, including DNA replication and gene expression. The DNA of prokaryotes is similarly associated/

Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from.

healthy females! All but 1 X chromosome are inactivated. Most mammals leave only 1 X chromosome activated in their cells. The inactivated chromosome(s) are called barr bodies! Remember! Chromosomal Mutations Error in replication: – Deletion: loss of a chromosomal segment – Duplication: repeat a segment/ for Duchenne Muscular Dystrophy, which is attributed to an X-linked gene. They have 4 children, 1 son with Duchenne, 1 carrier daughter and a daughter & son who are unaffected. The child with Duchenne /

Mutations. What are mutations? Mutations are changes in the genetic material. Types of Mutations: 1. gene mutations – changes in single gene 2. chromosomal.

the direction of parts of chromosomes Translocations - part of one chromosome breaks off and attaches to another Polyploidy - is the condition in which an organism has extra sets of chromosomes. Chromosomal Mutations Significance of Mutations Many mutations have little or no effect on gene expression. Some mutations are the cause of genetic disorders. Beneficial mutations may produce proteins with new or altered activities that can be useful.

Chapter 12: The Cell Nucleus and Control of Gene Expression.

workers installing the wiring only use the information related to their project. Brain cells only express genes related to brain activity and liver cells only express the genes related to their activity. The nucleus of most cells is typically amorphous and consists of: –The chromosomes (in the form of chromatin) –Nucleoli –Nucleoplasm –The nuclear matrix All surrounded by the nuclear envelope The Cell Nucleus… The nuclear envelope/

Specialized Mapping  Finding Chromosomal Locations  Using Tetrad Analysis To Study Genetic Distances (see Tetrad Analysis Web Module for Chapter 7 on.

-mouse hybrid cells with different numbers of human chromosomes (blue). Physical Chromosome Mapping How can we determine which chromosome carries a specific gene?How can we determine which chromosome carries a specific gene? In human-mouse hybrid cells, a 1:1 correspondence exists between the presence of the enzymatic activity for the gene and the presence of the chromosome carrying the gene. In human-mouse hybrid cells, a 1:1 correspondence/

L11 INTRODUCTION TO THE HUMAN CHROMOSOME. 1.Define the following terms relating to chromosome morphology: sister chromatids, centromere, p arm, q arm,

Tensin Homologue (PTEN): first identified in glioblastoma multiforma (aggressive brain tumor), inhibiting cell cycle progression and inducing apoptosis (as a negative regulator of Akt activation, opposing VEGF) Translocations Chromosomal translocation can rearrange the genome and activate “new” promoter/enhancer elements, dysregulating normal gene expression Chronic Myelogenous Leukemia (CML) – Philadelphia chromosome t(9,22), moving Abl to the “break point cluster” Bcr, resulting in chimeric fusion (Bcr/

Chromosomal Inheritance Chapter 15. Chromosomal basis of Inheritance Hereditary factors are located on chromosomes at specific loci - genes. Located in.

syndrome – XO Sterile Altered Chromosomal Disorders Cri du Chat –Deletion on chromosome 5 Leukemia – CML –Reciprocal translocation between chromosome 9 and 22 Chromosomal Mutations Bubble Map Summarize – give a specific example of a disorder caused by each. Genomic Imprinting Genes on autosomal chromosomes that are expressed depending on whether they come from the mother or father Insulin growth factor – only the paternal gene is activated –Maternal gene is imprinted - methylated/

Chapter 15 Chromosomal Basis of Inheritance

findings. What did they find? Chromosomes and genes are both present in pairs in diploid cells. Homologous chromosomes separate and alleles segregate during meiosis. Fertilization restores the paired condition for both chromosomes and genes. Chromosome Theory of Inheritance Mendelian genes have specific loci on chromosomes Chromosomes are what physically undergo segregation and independent assortment. Morgan first associated a specific gene with a specific chromosome. Morgan’s Fruit Flies Morgan first/

Lecture 45 Prof Duncan Shaw. Applications - finding genes Currently much interest in medical research, in finding the genes causing disease Sometimes.

called Candidate gene analysis Occasionally, disease is caused by a chromosome abnormality (e.g. Duchenne muscular dystrophy) - then you just find the gene that is disrupted Usually, have to find the gene by genetic mapping - use affected families and DNA polymorphisms /Gene Therapy for CF Gene therapy is the treatment of disease by introducing an active copy of defective gene –Ex vivo - remove some cells (e.g. bone marrow or blood) from patient, replace gene, return cells to patient –In vivo - deliver gene/


can be treated with intravenous injections of the missing protein. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings 2. Sex-linked genes have unique patterns of inheritance Although female mammals inherit two X chromosomes, only one X chromosome is active and one X chromosome condenses into a compact object, a Barr body  involves the attachment of methyl (CH3) groups to cytosine nucleotides on the X/

Viruses called bacteriophages can infect and set in motion a genetic takeover of bacteria, such as Escherichia coli Bacteria are prokaryotes with cells.

CYTOPLASM mRNA in cytoplasm Degradation of mRNA Translation Polypeptide Cleavage Chemical modification Transport to cellular destination Active protein Degradation of protein Degraded protein Regulation of Chromatin Structure Genes within highly packed heterochromatin are usually not expressed Chemical modifications to histones and DNA of chromatin influence both chromatin structure and gene expression Histone Modification In histone acetylation, acetyl groups are attached to positively charged lysines in/

Designer Genes (C)-2014 KAREN LANCOUR National Bio Rules National Bio Rules Committee Chairman

appearance of an organism Epigenetic factors can regulate the amount of gene activity, influencing the growth and appearance of an organism Malfunctions in epigenetic control of gene activity have been implicated in cancer, cardiovascular disease and several inherited genetic conditions Malfunctions in epigenetic control of gene activity have been implicated in cancer, cardiovascular disease and several inherited genetic conditions Phylogenetics Study of evolutionary relationships among groups of organisms/

Ch 14- 17 Unit Test Genetics.

in male embryos and masculinization of the gonads D) activation of SRY in females and feminization of the gonads B) formation of estrogens in female embryos All female mammals have one active X chromosome per cell instead of two. What causes this? A) activation of the XIST gene on the X chromosome that will become the Barr body B) activation of the BARR gene on one X chromosome, which then becomes/

MATTERS OF SEX Anueploidy Monosomy

embryo survives because it inactivates 2 X chromosomes and has only 1 functioning X chromosome in any given cell Trisomy 21 can not inactivate the extra copy of chromosome 21. So you have Down syndrome The only chromosome we can inactivate is the X chromosome Table 12.3 3 TYPES OF CHROMATIN Euchromatin true chromatin Heterochromatin Chromosomal regions that possess active genes Heterochromatin These regions stain darker than euchromatin/

Copyright © 2009 Pearson Education, Inc. PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey.

Tail Flow through nuclear envelope Broken- down mRNA CYTOPLASM Breakdown of mRNA Translation mRNA in cytoplasm Broken- down protein Cleavage / modification / activation Breakdown of protein Polypeptide Active protein NUCLEUS DNA unpacking Other changes to DNA Addition of cap and tail Chromosome Gene RNA transcript Gene Transcription Intron Exon Splicing Cap mRNA in nucleus Tail Flow through nuclear envelope Broken- down mRNA CYTOPLASM Breakdown of mRNA Translation/

AP Biology 2007-2008 From Gene to Protein How Genes Work.

can release amino acid at ribosome easily activating enzyme anticodon tRNA Trp binds to UGG/ Biology From nucleus to cytoplasm… Where are the genes?  genes are on chromosomes in nucleus Where are proteins synthesized?  proteins made/gene… “Defining a gene is problematic because… one gene can code for several protein products, some genes code only for RNA, two genes can overlap, and there are many other complications.” – Elizabeth Pennisi, Science 2003 gene polypeptide 1 polypeptide 2 polypeptide 3 RNA gene/

LECTURE 04: CHROMOSOMAL BASIS OF INHERITANCE I Fhow do we know that genes are parts of chromosomes? Fhow are they arranged on chromosomes? Fare chromosomes.

chromosome topography small chromosome structure  CHROMOSOMES - n n CHROMOSOMES - CENTROMERE Falso... (d) acentric and (e) dicentric... later! CHROMOSOMES - n, SIZE, CENTROMERE CHROMOSOMES - TOPOGRAPHY Fhuman nucleus, metaphase, n = 23 Fcentromeres - note positions Fchromomeres - bead-like thickenings CHROMOSOMES - TOPOGRAPHY Ftomato nucleus, prophase I, n = 12 Fcentromeres - orange Fheterochromatin - green: dense, note position... later Feuchromatin - white: less dense, active genes... later CHROMOSOMES/

NOTES: Ch 15 - Chromosomes, Sex Determination & Sex Linkage

development ● If a female is heterozygous for a particular gene located on the X chromosome, she will be a mosaic for that character Two cell populations in adult cat: Active X Early embryo: Orange fur X chromosomes Cell division and X chromosome inactivation Inactive X Inactive X Black fur Allele for orange fur Allele for black fur Active X Tortoise-shell cats! (a.k.a. “Torties”) XBXb/

 Chapter 15~ The Chromosomal Basis of Inheritance.

 Chapter 15~ The Chromosomal Basis of Inheritance  Genes have specific loci on chromosomes and chromosomes undergo segregation and independent assortment  Morgan  Drosophilia melanogaster  XX (female) vs. XY (male)  Sex-linkage: genes located on a sex chromosome  Linked genes: genes located on the same chromosome that tend to be inherited together  During crossing over in meiosis: some genes DO NOT assort independently of each other but are often inherited together  Genetic mapsThe further apart/

Remington Grenier, Mercedes Cote, Tyana Nowlan, and Rebecca Isaacs.

. Not all cells inactivate the same X. As a result, different cells will have different active X chromosomes. Linkage Linked genes are genes along the same chromosome that tend to be inherited together because the chromosome is passed a long as a unit. Linked genes lie on the same chromosome and do not follow Mendel’s law of independent assortment. Recombinant offspring exhibit new combinations of traits inherited from/

DNA and RNA.

can see through a light microscope in dividing cells The tight packing of nucleosomes may help separate chromosomes during mitosis There is also some evidence that changes in chromatin structure and histone-DNA binding are associated with changes in gene activity and expression Chromosome Structure What do nucleosomes do? Nucleosomes seem to be able to fold enormous lengths of DNA into the tiny space available in/

1 Diagnosis and treatment of autism considering features of the genetic background and metabolic status Ukrainian Institute of Clinical Genetics of KNMU.

connected with imprinting loss leading to inactive gene activation or inhibition of active gene expression; b)cancer diseases caused by hypermethylation of promoters of tumor suppressor gene 2. Diseases caused by global disorders of genome methylation in the result of de novo mutations in somatic cells – cancer disease connected with the global genome hypomethylation leading to activation of oncogenes, retrotransposons and chromosomal instability 72 Methionine Methionine – an essential/

The Chromosomal Basis of Inheritance

l k Sex Chromosomes and sex-linked genes: XX = female XY = male Father’s gamete determines sex of child Presence of a Y chromosome (SRY genes) allows development of testes/male characteristics Inheritance of sex-linked genes Sex-linked gene = gene carried on sex chromosome (usually X)/ Hemophilia Fragile X (Baldness & red-green color-blindness) X Inactivation: females have two X chromosomes, but only need one active X One X condenses in each cell during embryonic development  Barr body Females are a “/

(Long) Non-Coding RNAs

females relative to XY males. To balance X-linked gene expression levels in males and females, female cells invoke a mechanism (X chromosome inactivation, XCI) to randomly silence one of the maternal X chromosomes (Xm) during early embryogenesis.   Prior to cell differentiation: both X chromosomes are active (Xa) X chromosome inactivation In mammals females carry two X chromosomes whereas males carry only a single X giving a double/

Inborn chromosomal abnormalities 5th year RNDr Z.Polívková.

reciprocally imprinted genes PWS region – active paternal elleles AS region - active maternal allele loss of function of active alleles in PWS region (pat) loss of function of active allele in AS region (mat) → functional nullisomy Imprinted genes on chromosome No 15 normal situation pat mat SNRPN ZNF127 } } PWS genes AS gene active paternal elleleactive maternal allele „silent“= imprinted paternal allele „silent“=imprinted maternal allele UBE3A Deletion in PWS and AS pat/

Sex chromatin bodies Barr body.

requirements for mechanism of determination: 1. It represses gene activity 2. It is permanent. To check this hypothesis Peter Jones and Lawrence Shapiro grew cells in the presence of drug 5-azacytosine, which prevents DNA methylation. This reactivated the lyonized the X chromosome. Furthermore, Shapiro showed these reactivated chromosomes could be transferred to other cells and still remain active. X-inactivation facts about calico cats What determines/


the same DNA duplex, while the transcription factors are said to be trans-acting, acting on both copies of a gene on each chromosome being synthesized from genes that are located at a distance. DNA sequences that increase transcriptional activity, such as the GC and CAAT boxes, are known as enhancers. There are also negative regulatory elements or silencers that inhibit transcription. In addition, there/

Sex Determination in Humans

Michael Cummings ©2006 Brooks/Cole-Thomson Learning Lyon Hypothesis One X chromosome is genetically active in the body cells; the second is inactive and tightly coiled Either the maternal or paternal chromosome can be inactivated Inactivation is permanent (reset in germ cells) Inactivation of second X equalizes the activity of X linked genes in males and females ROSENSTIEL AWARD - Mary Lyon (+ others) 2007 Chapter 7 Human Heredity/

DNA and Chromosomes 4TH Edition Chapter 4. DNA and Chromosomes

location in heterochromatin regions if they are to be expressed. Position effect Observed in many organisms and thought to reflect an influence of the different states of chromatin structure along chromosomes on gene expression. The activity of a gene depends on its position along a chromosome When a gene that is normally expressed in euchromatin is experimentally relocated into a region of heterochromatin, it ceases to be/

Bio 402/502 Section II, Lecture 6 Chromosome territory and nuclear organization Dr. Michael C. Yu.

co-association Cis-interaction/trans interaction Speckle Chromatin loop Transcription factory Models of the chromosome territory (Heard & Bickmore, 2007) Interchromosome domain Interchromatin compartment The lattice model Models of the chromosome territory: interchromosome domain (Heard & Bickmore, 2007) Interchromosome domain: -Boundary between the surface of a CT and gene expression machinery compartment -Predict active genes are all located at the surface of CTs Splicing-factor enriched speckles (red/

Biology B_4 Heredity PART 1 (Chapters 11 and 14) (B-4.5-8) Demonstrate an understanding of the molecular basis of heredity. Website with good review images.

Austrian Monk) 1852 Performed experiments using pea plants and which where the basis for understanding genetics. Mendel’s LAW explains how GENES are passed from one generation to the next ACTIVITY – Children resemble their parents: http://dnaftb.org/1/ http://dnaftb.org/1/ WALTER SUTTON 1902 Developed the Chromosome Theory of Heredity… states that GENES are located on CHROMOSOMES Mendel’s Experiment: PROBLEM: How are traits/

Chromosomal Basis of Inheritance

equalize their X proteins, hermaphrodites turn down the activity of all the genes on the X chromosome at once by 50%. In Drosophila instead of reducing the gene activity in the XX female, flies double the activity of all the genes expressed on the males single X. Once upon a time There was a perfectly normal pair of chromosomes; X and Y diverged about 300 million years ago. What/

Genes and Chromosomes The Chromosome Theory of Heredity Mutations Regulation of Gene Expression.

nondisjunction result in chromosomal mutations? Regulation of Gene Expression Gene interactions – Incomplete dominance – Codominance – Polygenic inheritance Gene expression in prokaryotes – Operon – Repressor – Gene activation Gene expression in eukaryotes Regulation of Gene Expression As biologists have intensified their studies of gene activity, it has become clear that interactions between different genes and between genes and their environment are critically important Gene Interactions Dominance – How/

Genome Organization.

Chapter 12: Organization in Chromosomes Specialized Chromosomes Reveal Variations in the Organization of DNA Polytene chromosomes and lampbrush chromosomes are very large and can be visualized by light microscopy. Polytene chromosomes: have distinctive banding patterns represent paired homologs are composed of many DNA strands Polytene chromosomes have puff regions where the DNA has uncoiled and are visible manifestations of a high level of gene activity. Lampbrush chromosomes - large and have extensive DNA/

May 15 8:50 a.m. Make Up Exam For only one missed midterm Bring scantron and I.D.

X Y chromosome has less than 100 genes ……………….. One gene is for …… X Y Additional genes found on Y chromosome Inability to see and hear the obvious gene Inability to express affection over the phone gene Posturing in presence of other males gene Refusal to ask questions when lost gene Channel flipping gene Male Sports Bonding gene Addiction to death and destruction movies gene Preadolescent rock throwing gene Preadolescent attraction to spiders and insects gene Spitting gene Male/

Meiosis Vocab Heredity – the passing of traits/genes from one generation to the next Genetics – the study of heredity Genes – segments of DNA that code.

chromosomes (46) Homologous chromosomes – identical chromosomes …same length, centromere, same staining pattern …exception…males sex chromosome 1-22autosomes 23sex chromsomes Human female karyotype 46 chromosomes 23 pairs Human male karyotype 46 chromosomes 23 pairs Homologous chromosomes Paired chromosomes – both chromosomes of a pair carry “matching” genes/ Assortment of homologous chromosome in meiosis I 2.Crossing over during prophase I 3.Random fertilization of egg and sperm http://www./active Hela Cell

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