Chapter 7: Genetics Lesson 3: Human Genetics and Biotechnology
Goal 3 DNA, Protein Synthesis, Genetics, Biotechnology and Evolution.
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Transcript of Goal 3 DNA, Protein Synthesis, Genetics, Biotechnology and Evolution.
Goal 3DNA, 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 DNA (deoxyribonucleic
acid)forms a double-helix 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 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 AcidSingle 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 ribosomeRibosomal RNA – what the ribosome is
made of
Protein Synthesis
Two Steps
Transcription – copying DNA code onto the mRNA
Translation – making protein in the ribosome
Protein Synthesis
Transcription – DNA unwinds and
unzipsmRNA nucleotides
match up to the complimentary DNA nucleotide
Single strand of mRNA is made with the DNA code
Protein Synthesis
mRNA leaves the nucleus and carries the code to the ribosome
Protein Synthesis
Translation –mRNA lines up in the ribosomemRNA triplet codes (codons)match up with
tRNA triplet codes (anticodons)
Protein Synthesis
Translation continuedAmino acids are put in correct sequence.Peptide bond forms between amino acids.Polypeptide folds into protein.
Protein
Reading and interpreting an mRNA codon chart
Find each codon (3 base sequence) from the mRNA
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 inHydra.
Asexual Reproduction
Cutting of a plant
Mitosis
Occurs in all body cells Results in 2 new genetically identical
daughter cells Maintains the chromosome number Chromosomes DOUBLE then SPLITExample: humans 46 92 46
Stages of Mitosis
1. DNA (chromosomes) replicate
2. Spindle forms, nuclear membrane disappears
3. Chromosomes line up along the equator
4. Spindle fibers shorten, bringing chromosomes towards poles
5. Cytoplasm divides
Replicated chromosme
Replicated chromosome is actually two identical chromosomes attached at the centromere
Meiosis
Occurs only in the sex organs (testes and ovaries)
Results in 4 gametes (sex cells) Reduces the chromosome number in
half (for sexual reproduction) Chromosomes DOUBLE SPLITSPLITExample: human 46924623
Stages of Meiosis
1. DNA replicates2. Chromosomes line
up along the equator
3. Replicated pairs split
4. Chromosomes line up again
5. Centromere splits
Sources of variation
Crossing over (only occurs during meiosis).
Sources of Variation
RandomAssortmentOf chromosomes
Sources of Variation
Gene mutation
Nondisjunction
Fertilization
3.03 Patterns of Inheritance 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.
He studied seven different traits.
Genetic Vocabulary
Dominant- allele which masks the phenotype of other alleles
Recessive – allele that will not be expressed if dominant allele is present
Genetic Vocabulary
Heterozygous (hybrid) – the
genes in the
gene pair are
differentHomozygous (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
F1 Generation
F2 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 pigb – white guinea pigBlack guinea pig – BB or Bb?
BB x bb Bb x bbResult: only black Result: blackoffspring 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 Tools used by
scientists to trace inherited genes through a family tree
Squares= male Circle=female Filled=affected Half filled = carrier Empty=not affected
Polygenic Traits Traits which are
coded for by more than one allele.
Usually results in a blending of traits (ex: eye color, skin color, hair color)
Polygenic – Skin color
Human Genetics
Examples of single gene, autosomal inheritance patterns:
Sickle Cell AnemiaCystic FibrosisHuntington’s Disease
Sickle Cell Anemia
RecessivePredominantly in
people of African/African- American descent.
Hybrid individuals are resistant to malaria
Symptoms: tired, pain in joints
Cystic Fibrosis
RecessivePredominantly in
caucasiansSymptoms: mucous
clogs lungs and other organs, individuals usually don’t live past 20 years old
Huntington’s Disease
DominantSymptoms: 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
Gene for these traits are found on the X chromosome, but not the Y because it is so short
Recessive
Sex Linked Traits
Hemophilia Defective gene
prevents the normal formation of the proteins for clotting (platelets)
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
Example: a cow or pig has a human gene
Used to make human insulin by inserting human gene in bacteria
Firefly DNA inserted into tobacco plant
Transgenic Cow
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 lifeExamples: flies from
meatMice from ragsFrogs 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. Prokaryotic anaerobic heterotrophic organisms
2. Prokaryotic autotrophs started to produce oxygen and change the ancient atmosphere
3. Eventually enough oxygen was present in the atmosphere to promote the evolution of aerobic organisms
Evidence for Evolution
Fossils
Biochemicalsimilarities
Shared anatomicalstructures
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
Similarembryologicaldevelopment canshow closeevolutionaryrelationships.
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 SelectionRecent Examples
Resistance to Pesticides