1. Sexual Reproduction & Genetics

2.  Chromosome – a structure in the nucleus consisting of 1 long thread of tightly coiled DNA  DNA – nucleotides that provide the blueprint for the synthesis of proteins by the arrangement of nitrogenous bases

3.  Gene – a specific location on a chromosome, consisting of a segment of DNA, that codes for a particular protein  deter. the characteristics of an organism  Each chromosome consists of 100s of genes  Genes control each trait of a living thing by controlling the formation of an organism’s proteins

6.  Began the study of genetics in 1860  Genetics - The study of patterns of inheritance & variations in organisms  Used garden peas b/c of their availability, easy to control & mate, & distinguishing characteristics

7.  Since all cells’ (except gametes) chromosomes are diploid each cell contains 2 genes for each trait, 1 on the maternal chromosome & 1 on the paternal chromosome

8.  The 2 genes may be of the same form or they may be of different forms  These forms produce the different characteristics of each trait  The different forms of a gene are called alleles  The 2 alleles are segregated during the process of gamete formation (meiosis II)

9. 1.) Law (Principle) of Dominance: - states that some alleles are dominant whereas others are recessive - dominant allele for a particular trait will always have that trait expressed (seen) in the organism – represented by a capital letter – ex.) D, R - recessive allele for a particular trait will only have that trait expressed when the dominant allele is not present – represented by a lower case letter – ex.)d, r

10.  Since organisms received 1 gene for a chromosome pair from each parent, organisms can be either:  Homozygous – has 2 identical alleles for a particular trait – ex.) DD, dd  Heterozygous – has 2 different alleles – one is dominant & the other is recessive – ex.) Ff

11.  Genotype – the genetic makeup  the type of alleles an organism has inherited for a particular trait  Represented by a letter ▪ TT – homozygous dominant genotype ▪ tt – homozygous recessive genotype ▪ Tt – heterozygous genotype

12.  On a half sheet of paper answer the following questions: 1.) Which of the following show the genotype of a homozygous individual:Aa BB cc Dd EE 2.) What do we call the letter combinations in the question above?

13.  Phenotype – physical characteristics  Description of the way that a trait is expressed in the organism ▪ organisms w/ genotypes of “TT” or “Tt” would have a phenotype of “tall” ▪ organisms w/ the genotype “tt” would have the phenotype of “short”

14. 2.) Law (Principle) of Segregation - explains how alleles are separated during meiosis - each gamete receives 1 of the 2 alleles that the parent carries; so each gamete has the same chance of receiving either one of the alleles for each trait - during fertiliz. (when sperm & egg unite), each parent donates 1 copy of each gene to the offspring

15. 3.) Law (Principle) of Independent Assortment: - states that the segregation of alleles of 1 trait doesn’t affect the segregation of the alleles of another trait - genes on separate chromosomes separate indep. during meiosis - this holds true for all genes unless the genes are linked (they are in close proximity on the same chromosome)

16.  Used to predict the probable genetic combinations in the offspring that result from different parent allele combinations that are independently assorted  Monohybrid Cross – examines the inheritance of 1 trait  Dihybrid Cross – examines 2 different traits

20.  Basic principle that states genes are located on chromosomes & the behavior of chromosomes during meiosis accounts for inheritance patterns (which parallel Mendelian patterns)  So Mendel’s Laws support this theory  B/c of technology, patterns & variations not explained by Mendelian genetics are now understood by this theory

21. SO WHAT DID MENDEL’S LAWS OF GENETICS NOT EXPLAIN:

22.  Simply means that genes that are located on the same chromosome will be inherited together  These genes travel together during gamete formation  The exception to Mendel’s law of indep. assortmt

23.  Process in which alleles in close proximity to each other of homologous chromosomes are exchanged  When the homologues pair up in prophase I, sections of the chromosomes become crossed, these crossed sections may break off & usually reattach  When the genes are rearranged, new allele combinations are formed

24.  Crossing over explains how low linked genes can be separated resulting in greater genetic diversity

25.  A condition in which 1 allele is not completely dominate over another  The phenotype expressed is somewhere btw the 2 possible parent phenotypes

27.  Occurs when both alleles for a gene are expressed completely  The phenotype expressed shows evidence of both alleles being present

28. Eat More Chickn!!!!

29.  Can exist for a particular trait even though only 2 alleles are inherited  Ex.) 3 alleles exist for blood type (A, B, &O) which can result in 4 different blood types

31.  Traits that are controlled by 2 or more genes  Show a great variety of phenotypes  Ex.) skin color

33.  The result of genes that are carried on either the X or Y chromosome  An exception to the law of indep. assortmt  In organisms that undergo sexual repro., 1 pair of chromosomes (sex chromosomes) deter. the sex of the organism

34.  The pair of sex chromosomes in females consists of 2 “X” chromosomes, each carrying the same genes  The pair of sex chromosomes in males consist of 1 “X” and 1 “Y” chromosome

36.  In humans, the “Y” chromosome carries very few genes; the “X” contains a # of genes that affect many traits  Genes on sex chromosomes are called sex- linked genes  These genes are expressed differently from an autosomal gene (genes on the other 22 pairs of chromosomes)

37.  Female offspring will inherit the gene as they do all other chromosomes (X from dad, & X from mom) – law of dominance will apply  Females will only express the gene if both X chromosomes have the gene  Male offspring will inherit the gene on their X chromosome, but not on the Y  Since males have only 1 “X” chromosome, they express the allele whether dominant or recessive ▪ They don’t have a 2 nd “X “to mask the effects

38.  Color Blindness  Located on X chromosome ▪ X chromosomes carrying a gene for normal vision can be coded X C ▪ X chromosomes carrying a gene for color blind vision can be coded X c ▪ Y chromosomes that all lack this gene can be coded Y

39.  Only offspring that have X C gene will have normal vision

41.  Hemophilia is also a sex-linked trait  In rare cases, a female can express the sex- linked, recessive trait

45.  A chart that shows inheritance patterns (trait, disease, disorder) w/in a family  Shows multiple generations  Used to track the genotype & phenotype of family members  Dom/rec, sex-linked can be deter.

50.  An alteration of an organism’s DNA  Can range from a change in 1 base pair to the insertion or deletion of large segments of DNA  Can result from meiotic malfunctions or exposure to a physical or chemical agent (a mutagen) SQUIRREL!!!

51.  Most mutations are automatically repaired by the organism’s enzymes – no effect  But if not repaired, the altered chromosome or gene structure is then passed to all subsequent daughter cells of the mutant cell  This may have adverse or beneficial effects on the cell, organism & future generations

52. 1.) a body cell (somatic cell), daughter cells can be affected, but mutation won’t be passed to the offspring - can contribute to the aging process or dvlpt of many types of cancer

53. 2.) a gamete (sex cell), the altered DNA will be transmitted to the embryo & may be passed to subsequent generations – genetic disorders  Affects a single gene – gene mutation – Sickle Cell  Affects a grp of genes or whole chromosome – chromosomal mutation ▪ Nondisjunction – abnormal # of chromosomes (meiosis) ▪ Down Syndrome, Turner Syndrome, Klinefelter’s Syndrome

54.  Changes that are useful for the organism in changing envir.  Phenotypes are favored by natural selection & increase in a pop.

55.  Fetal Testing  Genetic counseling  Noninvasive Procedures  Invasive Procedures