- Slides: 57
Genetics: Study of Heredity
Aim: What is Genetics? http: //www. youtube. com/watch? v=e. Ov. MNOMRRm 8
Sexual Reproduction: • Two parents • Half of the genetic information is received from one parent, half from the other. • Variation Evolution
Asexual Reproduction: • One parent • Offspring is identical to parent. • Clones- identical genetic copies.
Genetics: • Gregor Mendel- 1800’s • “Father of Genetics” • Pea plants: easy to grow • Contrasting traits • Easily self and cross pollinate. • From his studies, Mendel arrived at conclusions that are the basis for genetics today!
Additional Vocabulary • Genetics: Study of heredity • Heredity: Passing of genetic information from an organism to it’s offspring.
• Genes: units of heredity – Determines traits/ characteristics an offspring will have. – Located on chromosomes. – For each trait-> minimum of 2 genes. One from mom, one from dad. • There are many genes located on a Chromosome.
Hereditary Information: • DNA- deoxyribonucleic acid • Organic (C, H, O, N, P). • Double stranded • Organized in the form of genes located on the chromosomes.
Hereditary Information: cont. • Homologous chromosomes- are same size and shape (one from each parent) – This allows for crossing over and variation to occur. http: //www. youtube. com/watch? v=l. Jz. Z 7 p-47 P 8
Genotype vs. Phenotype: Genotype- genes Ex: B, b, S, s Phenotype-Physical appearance Ex: Fur Color, Fur Length http: //www. youtube. com/watch? v=j. HWJqzl. Hl 3 w
Genetic Recombination: • Sperm and egg combine to form a new cell. • New cell (offspring) has a complete set of genetic information (DNA). Each offspring is unique.
The Genetic Code: – Structure of DNA was discovered by 2 scientists: – 1953 James Watson and Francis Crick – Created a model known as the Double Helix a twisted ladder.
What is the structure of DNA?
Structure of DNA • Long chain of repeating units ( polymer) called • nucleotides. A nucleotide unit contains: 1. phosphate group O 2. deoxyribose (sugar) 3. nitrogenous base: – A- adenine – T- thymine – C- cytosine – G- guanine
Structure of DNA
One Strand of DNA • The backbone of the molecule is alternating phosphate and deoxyribose, a sugar, parts. • The teeth are nitrogenous bases. phosphate deoxyribose bases
Two Stranded DNA • Remember, DNA has two strands that fit together something like a zipper.
Types of nitrogen bases • A= adenine • G= guanine • C= cytosine • T= thymine
Structure of a Double Helix • Sides of the “ladder” are • • alternating phosphate group and deoxyribose sugar. “rungs” of the ladder are made of 2 nitrogenous bases. Specific pairings: – There is a weak Hydrogen bond Between the base pairs. – Structure as a double helix – When a cell goes through mitosis(cell division) the DNA must also make a copy of itself.
DNA by the numbers • Each cell has about 2 • • • m of DNA. The average human has 75 trillion cells. The average human has enough DNA to go from the earth to the sun more than 400 times. DNA has a diameter of only 0. 00002 m. The earth is 150 billion m or 93 million miles from the sun.
Aim: How does DNA replicate? Do Now: Please answer the questions on the handout found on the front desk, omit questions 5 -7.
Genetics Can Tell All G-Guanine C-Cytosine T-Thymine A-Adenine
Base Pairing • Which bases always • • match up? A-T G-C Adenine always binds with Thymine Cytosine always binds with Guanine
Steps of Replication: 1. DNA unwinds 2. DNA unzips 3. Old strands become templates for new strands 4. Result- 2 identical DNA molecules
Characteristics of a Double Helix • Proteins and Cell Functioning: – Proteins- long chains formed from 20 kinds of amino acids. – Sequence(order) of the amino acids influences the shape of the molecule. – Proteins include: enzymes, insulin, eye color, and skin color.
DNA- Protein Connection: – Genes contain coded information. – This information is used to make proteins that are required for it’s function and structure. – Ribosomes construct proteins based on the cell’s DNA code (combo of A, C, T, G’s). – Parent and offspring produce similar traits that is why there is resemblance between them. They produce similar proteins.
Aim: How does protein synthesis Work?
Protein Synthesis: • The building of protein molecules. • Synthesizing protein from DNA. • Proteins are chains of amino acids.
Steps: – Begins in the nucleus with DNA. – DNA code is read by a “ messenger molecule” messenger RNA; ; – m. RNA. – “messenger molecule: travels into the cytoplasm of the cell to the ribosome.
Steps cont. : – With the help of “transfer molecules” t. RNA amino acids move to the ribosomes to make proteins. – The ribosomes “reads” the code and a chain of amino acids is produced forming a protein. – ***Protein structure is determined by DNA***
RNA: • Ribonucleic Acid • Single stranded • Nitrogenous bases – A- adenine – U- uracil – C- cystosine – G- guanine
Types of RNA – Messenger RNA (m. RNA) Copies code from DNA Brings to ribosome – Transfer RNA (t. RNA) Brings amino acids to ribosome for protein assembly – Mutations: Alteration of DNA sequence. Causes a change in code carried for by the gene. Random, but can be increased because of chemicals, radiation.
Aim: What are different genetic mutations? • Do Now: Please complete the handout on the front desk.
Different Types of Mutations: • Original DNA Template C A A T G C T A C – 1. Substitution: one base pair for another. CAACGCTAC – 2. Deletion: missing a base. CAATOCTAC – 3. Addition: adding an extra base CAATAGCTAC – 4. Inversion: bases are rearranged. CAGATCTAC
Causes of Mutations • Environmental Conditions can affect how genes are expressed. – Ex. Himalayan rabbit – Warmer body temperature white fur – Colder body temperature black fur • ** Identical twins- separated- different • personalities Chemicals, hormones can activate a gene, causing certain proteins to be produced.
Genetic Engineering • Used to alter instructions in organisms. • Produce more desirable traits.
Selective Breeding: • Produces animals and plants with desirable traits. • Horse & donkey= mule. (outbreeding) • Ex. Larger, juicier fruits… • Pure dog, pure cat. (inbreeding)
Breeding continued: • ** In sexually reproducing organisms only mutations found on sex cells can be inherited by the offspring. • Mutations occurring in body cells will only affect that organism.
DNA and Individuality: • The order of the nitrogenous base pairs, • • A, T, C, G’s are what makes each person an individual and unique. This is because the order allows for certain proteins to be produced. In an organism every cell contains the same genetic code. However, each cell is different: hair cells, skin cells, liver cells, stomach cells.
Gene Expression. • Each cell only uses some of the genetic information from the chromosomes. • Certain parts of the chromosomes get “turned on” or “turned off. ”
Gene Manipulation: • Altering genes using enzymes • By manipulating the DNA in plant cells or animal cells; favorable offspring can be produced • Produce bacteria that can be beneficial.
Steps: • Cut DNA segment with enzymes • This segment can be spliced (moved) and attached to DNA of a new organism. • New organism will make the protein coded for by DNA code.
Biotechnology: • Apply technology to biology. • Applications of Biotechnology: – By using gene therapy and applying it to modern medicine scientists may: – Produce hormones, enzymes and other body chemicals. – Provide at a low cost. – Provide a purer form.