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. DNA (deoxyribonucleic acid) forms a double-helix shape 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. (In DNA, the sugar is DEOXYRIBOSE)
Hydrogen Bonds Weak hydrogen bonds attach the two strands of the DNA molecule. Located between the base pairs
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 – IMPORTANT: to ensure new cells receive a complete copy
RNA Ribonucleic Acid (Ribonucleic acid) Single strand. Uracil instead of thymine. Ribose instead of deoxyribose.
Types of RNA Messenger RNA – Copies DNA code & carries it from nucleus to ribosome TRANSCRIPTION Transfer RNA - carries amino acids from the cytoplasm to the ribosome TRANSLATION Ribosomal RNA – what the ribosome is made of
Protein Synthesis Two Steps Transcription – copying DNA code onto the m. RNA (in the nucleus) Translation – interpreting m. RNA code into an amino acid chain (protein)…at 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. m. RNA attaches to ribosome
Protein Synthesis Translation – m. RNA triplet codes (codons)match up with t. RNA triplet codes (anticodons) Amino acids are put in correct sequence according to the codon sequences Peptide bond forms between amino acids. Polypeptide folds into protein.
Protein
The Code Every three nitrogen bases on m. RNA is the code for one amino acid. This is called a CODON Find the amino acid for the following codons: AGU CCC Give a codon for Tryptophan (Trp)
MUTATIONS u An error in the DNA sequence is called a mutation. u POINT MUTATION: change in one base u FRAMESHIFT MUTATION: addition or deletion of a base POINT MUTATION
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
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 u Therefore: produces DIPLOID cells
Replicated chromosme u Replicated chromosome is actually two identical chromosomes attached at the centromere
Stages of Mitosis 1. 2. 3. 4. 5. DNA (chromosomes) replicate (during INTERPHASE) Spindle forms, nuclear membrane disappears Chromosomes line up along the equator Spindle fibers shorten, bringing chromosomes towards poles Cytoplasm divides
Examples of asexual reproduction Binary fission One cell divides into 2 equal size cells EX: bacteria, unicellular protozoa (amoeba, paramecia)
Asexual reproduction Budding in Hydra Formation of a growth on the organism; pops off BUD
Asexual Reproduction VEGETATIVE PROPAGATION Plants produce runners Cutting of a plant Strawberries, cucumbers
Asexual Reproduction SPORES u Special asexual cells u Mushrooms, molds u
Asexual Reproduction REGENERATION u Replacing lost body part u If this results in MORE organisms than originally…it is a form of asexual reproduction u EX: cutting a worm or breaking up a starfish u
Asexual Regeneration CLONING u Creating genetically identical offspring u
CANCER Uncontrolled cell growth u Rapid mitosis u Abnormal cells grow faster than normal cells; take nutrients from healthy cells u Take over like “weeds” in a garden u
Meiosis u Occurs only in the sex organs (testes and ovaries) u Results in 4 daughter cells: gametes (sex cells) u Reduces the chromosome number in half (for sexual reproduction) u Chromosomes DOUBLE SPLIT (2 cell divisions) u Therefore: cells will be HAPLOID
Fertilization When 2 haploid sex cells unite, the diploid number is restored in the offspring (ZYGOTE) u MEIOSIS ensures that the diploid chromosome # is preserved generation after generation u If gametes formed the same way all cells formed (mitosis), then the chromosome # would double in each generation u After fertilization…the zygote divides by mitosis u
Stages of Meiosis 1. 2. 3. 4. 5. DNA replicates Chromosomes line up along the equator in homologous pairs Replicated pairs split Chromosomes line up again Centromere splits
Sources of variation Crossing over (only occurs during meiosis). Parts of homologous chromosomes break & recombine (switch places) deletion translocation inversion This increases genetic variety
Sources of Variation *Random assortment of chromosomes *Gene mutations
Sources of Variation u Nondisjunction failure of chromosome pairs to separate during meiosis EX: Down Syndrome
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; always expressed u Recessive – allele that will not be expressed if dominant allele is present u
Genetic Vocabulary Heterozygous (hybrid) – the alleles in the gene pair are different Homozygous (pure) – the alleles are the same in gene pair
Genetic Vocabulary Genotype – The actual genes of an organism (homozygous or heterozygous) Phenotype – What an organism actually looks like. (purple or white; tall or short
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
Genetic Vocabulary Parental generation (both parents homozygous) F 1 Generation (results of P cross) F 2 Generation (offspring of cross b/w 2 F 1 parents
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.
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 Dominance Punnett Squares
Co-dominance Co-dominant alleles result in the expression of both traits. Examples: roan horses (red X white); “blue” feathers in chickens (black X white)
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 Most 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
Multiple Alleles & Blood Types There are 3 alleles for blood type: A, B, o A and B are codominant. O is recessive.
Punnett Square – Blood Types
Polygenic Traits which are coded for by more than one pair of genes (many alleles. u Usually results in a blending of traits (ex: eye color, skin color, hair color; human height) u
Polygenic – Skin color
Human Genetic Disorders Examples of single gene, autosomal inheritance patterns: Sickle Cell Anemia Cystic Fibrosis Huntington’s Disease Result from mutations
Sickle Cell Anemia Codominant Red blood cells are sickle shape rather than round…don’t carry oxygen well Predominantly in people of African/African. American descent. Heterozygous 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 Both parents must be carriers to inherit
Huntington’s Disease Dominant Symptoms: Abnormal body movements, gradual deterioration or loss of intellectual abilities (dementia), behavior problems If one parent has it, you have 50% chance of having it
Karyotypes What is the sex of this individual? u u Show arrangement of chromosomes Amniocentesis: procedure that removes some amniotic fluid from where baby is developing in womb…contains cells
Karyotypes What disease does this individual have?
Pedigrees u chart used by scientists to trace inherited genes through a family tree u Squares= male Circle=female Shaded = affected Half shaded = carrier Unshaded=not affected u u
3. 04 Biotechnology & Genomics
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. IMPLICATION: fix defective genes! Prevent genetic disorders!
Gel electrophoresis DNA fragments separate according to size
Gel Electrophoresis Creates a DNA fingerprint. Everybody’s DNA is unique…everybody’s DNA fingerprint is unique Used in crime scene investigations; paternity cases; determine how closely related organisms are.
Transgenic Organisms Having DNA from another species u Example: a cow or pig has a human gene u Firefly DNA inserted into tobacco plant
Transgenic Cow u Organisms that have DNA from a different Species of organism 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 u Human Insulin has been made by inserting a human gene for making insulin into bacteria; bacteria reproduce every 20 minutes…therefore they quickly produce insulin that can then be given to people who need insulin such as people with diabetes
Biotechnology Ethical issues and implications: Stem Cell Research "Stem" cells offer much hope for medical advancement because of their ability to grow into almost any kind of cell. EX: *damaged nerve cells can be replaced *in treatment of cancer, cells destroyed by radiation or chemotherapy can be replaced with new healthy stem cells Dead cells of almost any kind, no matter the type of injury or disease, can be replaced with new healthy cells thanks to the amazing flexibility of stem cells
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 Change in species over long periods of time Change from simpler organisms to more complex Evolved from a common ancestor
ORIGIN OF LIFE BIOGENESIS u Life comes only from living things ABIOGENESIS u Life can come from something nonliving u Also called SPONTANEOUS GENERATION Examples: flies from meat Mice from rags Frogs and insects from mud
Francesco Redi proved flies were not spontaneously generated from rotting meat He placed meat in jars and sealed half. He left half the jars open. A few days later, the open jars were full of maggots & flies Biogenesis
Biogenesis Louis Pasteur used specially made flasks and broth to prove biogenesis He showed that microorganisms were not spontaneously generated from air
Oparin’s Theory on the Origin of u Oparin believed Life that life could have been created from conditions of early earth. u He believed the combination of gases, volcanic activity, electricity from storms could have produced the first organic molecules
Early Earth – Miller & Urey Experiment Sparks (lightning) Gases (volcanoes) Water droplets (rain) Heat (geothermal) NO OXYGEN 1 week = amino acids
ANAEROBIC & HETEROTROPHIC & PROKARYOTIC As food became scarce…organisms developed the ability to manufacture their own food (plants) A by-product of this process was OXYGEN! Evolution to AEROBIC & AUTOTROPHIC organisms First Organisms
Evolution of eukaryotic cells
Evidence for Evolution Fossils Biochemical similarities Shared anatomical structures Similar Embryonic stages
Patterns in the fossil record What can they tell us? The most primitive organisms are the oldest. (near the bottom) The most advanced organisms are the youngest. (near the top)
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. (C 14)
Biochemical similarities Comparing similarities of organic molecules such as DNA or amino acid sequences
Embryology Similar embryological development can show close evolutionary relationships. Humans, rabbits, fish show similar embryonic stages
Homologous Structures Four different mammal limbs have the same basic bone structure but different functions may suggest common ancestry
Vestigial Structures that have little purpose in an organism u These structures may be incomplete or disappearing u Suggest the structure once had a purpose u
Theory of Evolution Charles Darwin Theory of natural selection Jean Baptiste Lamarck Theory of acquired characteristics
NATURAL SELECTION Environment favors individuals with better adapted variations u Therefore those individuals will most likely survive to reproduce offspring with those desired traits u Variations stimulate natural selection
Adaptive Radiation Several species evolve from a single ancestral species u New species all in close proximity of each other u Evolve because of adaptations to specific environmental conditions u
Geographic Isolation Organisms evolve into new species because they are separated by geographic barriers such as rivers, canyons, mt ranges, islands Examples: Kaibab squirrel (top) and the Albert squirrel (bottom) from the Grand Canyon Galapagos finches
Natural Selection Recent Examples
Antibiotic Resistance u u Antibiotics were invented in early 1900’s and were a miracle drug… eradicated numerous deadly bacterial infections However, decades of antibiotic use has produced numerous strains of antibiotic resistant bacteria
Resistance to Pesticides u u u Overuse of pesticides cause some insects to evolve resistance to pesticides. Those pesticideresistant insects survive…reproduce…p assing their resistance to a new generation Each generation has more pesticideresistant bugs!
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