Goal 3 DNA Protein Synthesis Genetics Biotechnology and

Goal 3 DNA, Protein Synthesis, Genetics, Biotechnology and Evolution

3. 01 DNA, RNA and Protein Synthesis DNA is the code of life. It contains the information on how to make proteins.

Structure of DNA u u u DNA (deoxyribonucleic acid)forms a doublehelix shape Consists of a sugar (deoxyribose), a phosphate, and a nitrogenous base Bases – Adenine-Thymine – Guanine-Cytosine (complementary base pairing)

Nucleotide –building blocks of DNA A nucleotide is made up of a phosphate group, nitrogen base (A, T, G, C) and sugar.

Hydrogen Bonds Weak hydrogen bonds attach the two strands of the DNA molecule.

DNA replication u u Copying of genetic material before mitosis and meiosis 3 steps – 1) DNA unzips at hydrogen bonds – 2) free nitrogenous bases join up to newly opened bases – 3) sugar-phosphate “backbone” rebuilt

The Code Every three nitrogen bases is the code for one amino acid. An error in a nitrogen base is called a mutation.

RNA Ribonucleic Acid Single strand. Uracil instead of thymine. Ribose instead of deoxyribose.

Types of RNA Messenger RNA – carries DNA code from nucleus to ribosome (why can’t DNA leave the nucleus? ) Transfer RNA - carries amino acids from the cytoplasm to the ribosome Ribosomal RNA – what the ribosome is made of

Protein Synthesis Two Steps Transcription – copying DNA code onto the m. RNA Translation – making protein in the ribosome

Protein Synthesis Transcription – DNA unwinds and unzips m. RNA nucleotides match up to the complimentary DNA nucleotide Single strand of m. RNA is made with the DNA code

Protein Synthesis m. RNA leaves the nucleus and carries the code to the ribosome

Protein Synthesis Translation – m. RNA lines up in the ribosome m. RNA triplet codes (codons)match up with t. RNA triplet codes (anticodons)

Translation. Protein continued. Synthesis Amino acids are put in correct sequence. Peptide bond forms between amino acids. Polypeptide folds into protein.

Protein

Reading and interpreting an m. RNA codon chart u u Find each codon (3 base sequence) from the m. RNA Use chart to find the correct amino acid that it codes for

Gene Regulation All cells of an organism have the same DNA. What type of cell develops depends on which genes get turned on or off. This is why a multicellular organism is able to differentiate into many types of cells. For example: skin cells, muscle cells, bone cells.

Gene Regulation Cells respond to their environment by producing different types and amount of protein. Examples: 1. You get cut and your skin cells need to make proteins to repair your skin. 2. Cancer may result when your cells make too many cells (protein). 3. Diabetes may result if your pancreatic cells don’t make enough insulin (protein).

3. 02 Cell Division 2 Types of cell division: 1. Mitosis – involved in growth, repair and asexual reproduction 2. Meiosis – involved in the production of gametes

Examples of asexual reproduction Binary fission

Asexual reproduction Budding in Hydra.

Asexual Reproduction Cutting of a plant

Mitosis u Occurs in all body cells u Results in 2 new genetically identical daughter cells u Maintains the chromosome number u Chromosomes DOUBLE then SPLIT Example: humans 46 92 46

Stages of Mitosis 1. 2. 3. 4. 5. DNA (chromosomes) replicate Spindle forms, nuclear membrane disappears Chromosomes line up along the equator Spindle fibers shorten, bringing chromosomes towards poles Cytoplasm divides

Replicated chromosme u Replicated chromosome is actually two identical chromosomes attached at the centromere

Meiosis u Occurs only in the sex organs (testes and ovaries) u Results in 4 gametes (sex cells) u Reduces the chromosome number in half (for sexual reproduction) u Chromosomes DOUBLE SPLIT Example: human 46 92 46 23

Stages of Meiosis 1. 2. 3. 4. 5. DNA replicates Chromosomes line up along the equator Replicated pairs split Chromosomes line up again Centromere splits

Sources of variation Crossing over (only occurs during meiosis).

Sources of Variation Random Assortment Of chromosomes

Sources of Variation u Gene mutation u Nondisjunction u Fertilization

3. 03 Patterns of Inheritance u u u Gregor Mendel Father of genetics Austrian Monk First noticed inheritance of traits Studied heredity in pea plants, and noted statistics included within monohybrid/dihybrid crosses

Mendel’s Experiments Results of Mendel’s crosses with pea plants. u He studied seven different traits. u

Genetic Vocabulary Dominant- allele which masks the phenotype of other alleles u Recessive – allele that will not be expressed if dominant allele is present u

Genetic Vocabulary Heterozygous (hybrid) – the genes in the gene pair are different Homozygous (pure) – the genes are the same

Genetic Vocabulary Geneotype – The actual genes of an organism Phenotype – What an organism actually looks like.

Genetic Vocabulary Parental generation F 1 Generation F 2 Generation

Law of Segregation During meiosis, the gene pair splits and each gamete only has one member of each pair of genes.

Law of Independent Assortment During meiosis, the genes in each gene pair move into the gametes independently of each other. Notice you can still get a 3: 1 ratio between yellow and green or round and smooth.

Genotype and Phenotype A change in the environment also can affect the phenotype. Although we often think of flamingos as being pink, pinkness is not encoded into their genotype. The food they eat makes their phenotype white or pink

Test Cross Mate unknown with a pure recessive. B – black guinea pig b – white guinea pig Black guinea pig – BB or Bb? BB x bb Result: only black offspring Bb x bb Result: black and white pigs

Incomplete Dominance Blending of two traits.

Incomplete Punnett Square

Co-dominance Co-dominant alleles result in the expression of both traits. Examples: roan shorthorn cattle of AB blood

Pedigrees u Tools used by scientists to trace inherited genes through a family tree u Squares= male Circle=female Filled=affected Half filled = carrier Empty=not affected u u

Polygenic Traits which are coded for by more than one allele. u Usually results in a blending of traits (ex: eye color, skin color, hair color) u

Polygenic – Skin color

Human Genetics Examples of single gene, autosomal inheritance patterns: Sickle Cell Anemia Cystic Fibrosis Huntington’s Disease

Sickle Cell Anemia Recessive Predominantly in people of African/African. American descent. Hybrid individuals are resistant to malaria Symptoms: tired, pain in joints

Cystic Fibrosis Recessive Predominantly in caucasians Symptoms: mucous clogs lungs and other organs, individuals usually don’t live past 20 years old

Huntington’s Disease Dominant Symptoms: Abnormal body movements, gradual deterioration or loss of intellectual abilities (dementia), behavior problems

Blood Types A and B are co -dominant. O is recessive.

Punnett Square - Blood

Sex Linked Traits Trait is more likely to be inherited by males u Gene for these traits are found on the X chromosome, but not the Y because it is so short u Recessive u

Sex Linked Traits Hemophilia u Defective gene prevents the normal formation of the proteins for clotting (platelets) u Symptoms: uncontrollable bleeding when cut

Sex Linked Traits Colorblindness Unable to distinguish between certain colors. For example – red/green color blindness

Karyotypes What sex is this individual?

Karyotypes What disease does this individual have?

3. 04 Biotechnology

Human Genome Project Scientists have uncovered the entire human DNA code. Information useful in screening for diseases, gene therapy and developing drugs.

Gene Therapy Inserting corrected gene into person who has a defective gene. Still in the experimental stages.

Gel electrophoresis DNA fragments separate according to size

Gel Electrophoresis Also called DNA fingerprinting. Used in crime scene investigations. Used to determine how closely related organisms are.

Transgenic Organisms Having DNA from another species u Example: a cow or pig has a human gene u Used to make human insulin by inserting human gene in bacteria u Firefly DNA inserted into tobacco plant

Transgenic Cow u A Dutch biotechnology company called Pharming has genetically engineered cows, outfitting females with a human gene that causes them to express high levels of the protein human lactoferrin in their milk

Transgenic Bacteria

Biotechnology Ethical issues and implications: Stem Cell Research

More controversy Genetically modified food (sometimes called Franken Food) Will it harm us? Will it harm the environment? Is it the future?

3. 05 Evolution Abiogenesis – Life can come from non life Examples: flies from meat Mice from rags Frogs and insects from mud

Biogenesis Francesco Redi used flies, meat and screens to disprove abiogenesis.

Biogenesis Louis Pasteur used specially made flasks and broth to prove biogenesis

Theory of Natural Selection Charles Darwin Naturalist on the British Ship the HMS Beagle

The Voyage

Galapagos

Iguanas and Tortoises

Finches and Boobies

Early earth Hypothesis that the first organisms to evolve were ANAEROBIC & HETEROTROPHIC & PROKARYOTIC

Early Earth - Experiments Experiment: Sparks (lightning) Gasses (volcanoes) Water droplets (rain) Heat (geothermal) NO OXYGEN 1 week = amino acids

Evolution of eukaryotic cells

Evolution of aerobic and photosynthetic organisms 1. 2. 3. Prokaryotic anaerobic heterotrophic organisms Prokaryotic autotrophs started to produce oxygen and change the ancient atmosphere Eventually enough oxygen was present in the atmosphere to promote the evolution of aerobic organisms

Evidence for Evolution Fossils Biochemical similarities Shared anatomical structures

Patterns in the fossil record What can they tell us? The most primitive organisms are the oldest. The most advanced organisms are the youngest.

Fossilization Relative Dating Finding the age by comparing the fossil to the rocks or fossils near by.

Fossilization Absolute Dating Using radioactive isotopes to determine age.

Biochemical similarities

Similar Structures Similar embryological development can show close evolutionary relationships.

Similar Structures Four different mammal limbs have the same basic bone structure.

Mechanisms of Evolution Variation (provides material) Geographic Isolation Environment (selection pressures)

Peppered Moth Variation provides material for natural selection.

Geographic Isolation Examples: Kaibab squirrel (top) and the Albert squirrel (bottom) from the Grand Canyon Galapagos finches Australia’s marsupials

Natural Selection Recent Examples

Resistance to Pesticides