Reporting Category 2 Organization of Living Systems

TEK 6A  Identify components of DNA, and describe how information for specifying the traits of an organism is carried in the DNA

General Information  Purpose: Genetic information is stored in DNA  Location: nucleus of living cells  Discovery: Watson and Crick discovered the 3D shape of DNA, now called the Double Helix  Structure:  Sugar phosphate backbone  Nucleotides (nitrogenous bases)

Matching and Bonding  Matching base pairs:  A-T  C-G  Bonds that hold DNA together:  Backbone: connected by covalent bonds  Bases: connected by hydrogen bonds

Example Questions 1. Why will knowledge of the human genome enable scientists to better understand proteins involved in human diseases? A: DNA contains the information used to make proteins 2. A particular strand of DNA has the base sequence ATT- CCG. What is the base sequence of the complimentary strand? A:TAA-GGC

TEK 6E  Identify and illustrate changes in DNA and evaluate the significance of these changes

What causes mutations? 1. DNA damage from environmental agents such as ultraviolet light(sunshine), nuclear radiation or certain chemicals 2. Mistakes that occur when a cell copies its DNA in preparation for cell division

Types of Mutations 1. Point mutation-change to one base in a gene sequence 2. Inversion- an entire section of DNA is reversed

Types of Mutations 3. Frame shift- one or more bases are inserted or deleted, like adding or removing letters in a sentence a. insertion-adding one or more bases to a gene sequence b. deletion-when one or more bases to a gene sequence are deleted (or missing)

Example Question

TEK 6F  Predict possible outcomes of various genetic combinations such as monohybrid crosses, dihybrid crosses and Non- Mendelian inheritance

Important Vocabulary  Dominant- an allele that is expressed or shown in the phenotype; it masks or hides recessive allele traits  Recessive- an allele that is not expressed or shown in the phenotype because it is hidden by the dominant allele  Homozygous- when an organism has the same alleles for a trait (can be dominant or recessive)  Heterozygous- when an organism has two different alleles for the same trait (dominant trait is shown)

Genotype vs. Phenotype Genotype Phenotype  Refers to the two alleles an individual has for a specific trait  Refers to the physical appearance of the individual

Mendelian vs. Non-Mendelian Genetics Mendelian Non-Mendelian  Law of Segregation  Each individual has a pair of alleles for each trait  Alleles segregate during gamete formation(egg and sperm)  Fertilization gives the offspring two alleles  Incomplete dominance  If an organism is heterozygous for a trait the phenotype is a blend of the two allele types  Codominance  An organism that has both alleles of a gene displays both phenotypes at the same time

Examples of Non-Mendelian Genetics

Monohybrid and Dihybrid crosses MonohybridDihybrid  After completing the punnett square answer the questions  1. what percent of the offspring will be short?  2. what percent will be tall?  What is the genotypic ratio for DdRr?

More Dihybrid Practice:  AABb x AaBb

TEK 6B  Recognize that components that make up the genetic code are common to all organisms

The Genetic Code  In all living organisms, the instructions for reproducing and operating the individual is encoded in DNA  The genetic code is universal  This leads scientists to believe organisms have a common ancestor

The Genetic Code  How many different codons code for Leucine (Leu)?  6  What does that lead you to believe about the genetic code and mutations to DNA?  That if one base pair changes, the mutation may have no effect if you still end up with the same amino acid

TEK 6C  Explain the purpose and process of transcription and translation using models of DNA and RNA

Central Dogma  Thesis that information flows from DNA to RNA to protein

Protein Synthesis  Protein Synthesis is divided into two processes:  Transcription and Translation  Transcription  A section of DNA is copied into mRNA; this takes place in the nucleus  Remember: RNA has U instead of T  Translation  mRNA codons are translated into amino acids with the help of tRNA.  A ribosome attaches the amino acids to form the protein  This takes place in the cytoplasm

Transcription and Translation

TEK 6D  Recognize that gene expression is a regulated process  express = “turn on”  Repress = “turn off”

Environmental Factors  The expression of genes in an organism can be influenced by the environment  Factors include:  Gender  Chemicals  Temperature  light

Gene Regulation  Gene regulation in eukaryotes takes place during each phase of the process  Chromatin Remodeling-the region of the chromosome must be open in order for the gene to be accessed  Transcriptional Control-most common type; can turn on or off mRNA  Translational Control-regulation of the rate; make an inactive protein active

TEK 6G  Recognize the significance of meiosis to sexual reproduction

Chromosome Structure  Chromosome: a single piece of coiled DNA containing many genes  Homologous Chromosome: each chromosome has a match. This is why you have 46(even number). You get 23 from each parent  Sex Chromosome: X and Y; determine the sex of the organism; XX= female, XY = male

Process of Meiosis  Meiosis: the production of haploid cells with unpaired chromosomes  Broken down into two phases:  Meiosis I  Meiosis II

Key points of meiosis  The process results in 4 daughter cells  Daughter cells are haploid(23 chromosomes)  Daughter cells have unique combinations of chromosomes  Daughter cells do not have homologous pairs  Meiosis creates gametes(sperm and eggs)  Meiosis ensures variability in offspring

Independent Assortment and Crossing over  Independent assortment: alleles for a particular phenotype determine what characteristic an organism will express  When alleles separate during metaphase I it is random which cell each allele ends up in  Crossing over:The exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.  This increases genetic variability

Mitosis vs. Meiosis

TEK 6H  Describe how techniques such as DNA fingerprinting, genetic modifications, and chromosomal analysis are used to study the genomes of organisms

Human Genome Project  Completed in 2003  13 year project  Goals:  Identify all the 20,000-25,000 genes in human DNA  Use data to improve medical technologies and treatments  Address ethical, legal and social issues

Manipulating DNA  Genetic Engineering is the process of reading and changing DNA sequences in an organism  1. DNA extraction  2. Cutting and Labeling DNA  3. Separating DNA  4. Reading the DNA sequence  5. Making copies(PCR)

Uses of Gel Electrophoresis  DNA Fingerprinting  Paternity tests, crime scene samples  Gel electrophoresis is used to separate the DNA sample into pieces  The position and length of bands are unique like a fingerprint  Material you can get samples from:  Blood  Hair  Saliva  Semen  Body tissue cells

Gel Electrophoresis