Heredity
Give an example of how heterozygous, homozygous dominant, and homozygous recessive alleles are written.
Heterozygous: Aa
Homozygous dom: AA
Homozygous rec: aa
What are the 4 nucleotide bases of DNA and how do they pair up?
Adenine (A), thymine (T), cytosine (C), guanine (G)
A-T
C-G
What are the 2 sources of influence on all traits?
genes and environment
Animals can be bred for any trait including patience
True (ie: foxes bred in Russia to make good pets, cows bred for greater patience while being milked, etc.)
Why is human evolution still only a theory rather than law or fact
We cannot prove human evolution in a lab setting because it takes too long, however, there is significant evidence in nature and related lab studies
what is the difference between phenotype and genotype?
A phenotype is the expression or physical appearance of specific alleles (brown eyes), a genotype is the combination of specific alleles (Bb)
What is the difference between introns and exons?
Exons are parts of DNA that code for proteins while introns do not. Introns perform other functions to regulate the DNA.
Ally and Sally are MZ twins who were separated at birth, they met up later in life and have more personality traits that are the same than different ones. Personality has a _________ (high/low) heritability. Why?
high. This is because Ally and Sally grew up in different environments with identical genes, yet they still ended up with similar personality traits. the variation between their personalities can be more explained by differences in environment than genes.
Are innate traits like appetite and other reflexes affected by envt?
Yes, ALL traits are affected by both genes and envt.
Did Darwin go on the Beagle to prove the theory of evolution? Why or why not?
No, he did not even know that evolution existed. He boarded the Beagle as a naturalist simply to gather specimens, take notes on what he found, and send what he collected back to England. Had no expectations and simply went with an open and curious mind and a question of, why are there so many different species and animals on the planet?
Explain the difference between mitosis v. meiosis (general steps included, final outcome, what each is responsible for)
Mitosis: chromosomes duplicate in the cell and split into identical cells resulting in daughter cells identical to the original cell (in humans 23 pairs of chromosomes)
Meiosis: the same first steps of mitosis but then split again, resulting in sister cells with half the original amount of chromosomes (in humans 23 chromosomes rather than 23 pairs of chromosomes), responsible for gametes
Explain the process of translation.
tRNA with an anticodon "reads" nucleotide bases in mRNA in groups of 3s (codons) brings amino acids according to the code. these amino acids string together to form a protein.
Describe the difference between heredity and heritability.
Heredity: how genes are passed down within family lines
Heritability: how differences in genes describe the difference between people/ populations
An adoptee has lots of personality traits in common with their adoptive parents and little in common with their birth parents. Personality has a __________ (high/low) heritability. How do you know?
Low, heritability is the percent of variance that can be explained by genes rather than the environment, an adoptee having more in common with adoptive parents is explained more by environmental factors than genetic factors
Birds and butterflies both have functional wings allowing them to fly in response to selection pressures. What is this called? Did they inherit these traits from a common ancestor?
The wings are analogous traits. Birds and butterflies both evolved wings to fly, to access food and escape predators, but they do not share this trait because of genetic similarity.
Huntington's disease is an autosomal dominant disease. Can two affected parents have an unaffected child? Draw a punnett square on the whiteboard.
Yes, if both parents have a heterozygous genotype there is a 25% chance of having an unaffected child.
Describe the 4 different types of mutations and give an example on the whiteboard of how they would affect the original strand
"ATT CTG ATG ..."
Point: a single nitrogenous base is replaced for another
ATT CTG TTG ...
Deletion: an entire codon is removed from the strand
ATT ATG ...
Insertion: an entire codon is added to the strand
ATT GAT CTG ATG ...
Frameshift: a single nitrogenous base is either added or removed without being replaced
AT*C TGA TGC. ...
Fix this sentence and explain why it is wrong:
Height has a heritability score of 0.80, 80% of your height is a result of your genetics and 20% is a result of your environment.
"Height has a heritability score of 0.80, therefor 80% of the variability of height in the population can be explained by variations in genetic composition."
What does "different genes interact with different environments differently" mean?
That the outcome of a certain trait is dependent on the interaction of different genes and different environments. Think about the maze rat study and how that applies.
Why are fecundity and survival to reproductive age important to evolution?
In order for genes to be passed on into the next generation and into the gene pool, individuals in the population must survive to reproductive age and produce fertile offspring, otherwise, once they die their genes disappear from the gene pool.
Two part question:
(1) Why are women less likely to be colorblind?
(2) Draw a punnett square on the whiteboard that shows how a woman can be colorblind.
(1) Colorblindness is a recessive x-linked disorder meaning the gene is carried on the x chromosome, women have 2 x chromosomes so in order for women to be colorblind they need to be homozygous recessive which is less common, even if they have one of the faulty alleles they have another x chromosomes to potentially make up for the faulty one.
(2) a woman can be colorblind in 2 scenarios:
- a colorblind father and a carrier mother
- a colorblind father and a colorblind mother
Why do we get frequent variants of viruses?
Once a virus enters a host cell it is really good at replicating itself and does so way more often than many other organisms, therefore, allowing more possibility for mutations, hence, variants.
How can the heritability of a trait change over time? In your explanation use eyesight as an example.
A trait may have different influences of genes v. envt among people due to introduction of new environmental influences.
Laser eye surgery is an environmental factor that lowers heritability, because now the reason why people have variation in the shapes of their cornea can be more due to environmental variations.
Draw the maze dull/ maze bright rats graph and describe what it means.
That the genes of the rats interact with different environments differently, to produce different expressed behavioral outcomes. the environment can and did either enhance or suppress the effects of the genes.
Darwin's theory of evolution by natural selection was inspired by the different beak shapes he observed among the finches of the Galapagos islands. How and why did these different beak shapes develop?
-Certain types of food were more abundant in diff areas of the Galapagos
-To survive, the birds needed to be able to access the type of food available in their area so those birds whose beaks were especially suited to the food in their region were more likely to survive and pass on their genes for beak type