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Biology 121 Final Exam > Exam 2 Content > Flashcards

Exam 2 Content Flashcards

1
Q

Who is Gregor Mendel?

A

Austrian monk who lived in the 1800s
The first person to come up with a quantitative way to deal with inheritance and come up with a mechanism of how it worked

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2
Q

what are alleles?

A

Alternative forms of genes
Different alleles available for each heritable characteristic

For each inherited characteristic a diploid organism has 2 alleles at each locus/each gene (one allele from each parent)

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3
Q

What is a locus?

A

Gene for a trait exists in a location (on homologous chromosomes)

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4
Q

What is the difference between homozygous and heterozygous chromosomes?

A

If the alleles are identical they are homozygous and true breeding(RR or rr)
If the alleles are different they are heterozygous (Rr)

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5
Q

What is a phenotype?

A

the physical appearance of an organism, more specifically what traits are expressed in an organism

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6
Q

what is a genotype?

A

the actual genetic makeup of an organism

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7
Q

what is incomplete dominance?

A

F1 and F2 have a intermediate between (1:2:1 phenotypic and genotypic ratio)

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8
Q

what is Epistasis?

A

One gene masks the effect of the other
1 gene has veto power
Biochemically one gene is further in the pathway than the other
Example: aa is epistatic over the b gene

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9
Q

what is Polygenic?

A

Multiple genes interacting
Human height
5 - 10 loci contribute to phenotype
Melanin is determined by 3 genes
Race is social construct not biological

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10
Q

what is Pleiotropy?

A

Single gene has many phenotypic characters
Sickle-cell anemia which leads to a complex set of outcomes

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11
Q

what is Penetrance?

A

Percent of individuals carrying the gene and showing the expected phenotype
Retinoblation (incomplete penetrance)
Not everyone that has the dominant allele has that problem

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12
Q

what is Expressivity?

A

Degree of which a gene is expressed
Mild, moderate, or severe

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13
Q

what are the 2 single gene defects?

A
  1. Autosomal (22 autosomes)
    Can be dominant or recessive
  2. Sex-linked (1 per sex chromosome)
    Can be dominant or recessive
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14
Q

how to read a human pedigree?

A

Circles = females
Squares = male
Filled in = phenotype of interest is present
Open = disease is not present

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15
Q

what are the characteristics of autosomal recessive diseases?

A

Parents are generally normal (non-expressive)
Siblings are the only affect relatives
Males and females have it at equal proportion
Parents are consanguineous
- Same blood line

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16
Q

what are the characteristics of Autosomal Dominant diseases?

A

You only need one bad allele

The affected individual will have ½ normal and ½ affected
Normal children of affected individuals will have normal kids
Males and females are affected in the same proportion
Each sex is equally likely to transmit it

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17
Q

What are sex-linked diseases?

A

Usually X linked
Females are homogenetic sex (XX)
Males are the heterogenetic sex (XY)

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18
Q

what are the characteristics of sex-linked diseases?

A

Higher in males than females
Phenotype is never transmitted from father to son

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19
Q

what is Eugenics?

A

Find an undesirable trait and eliminate them
Genetically modified baby
Screen eggs ahead of time

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20
Q

what did Chargaff discover?

A

Found A=T and C=G

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21
Q

what did Watson and Crick discover?

A

Proposed double-stranded helix
3 billion base pairs

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22
Q

what did Meselson and Stahl discover?

A

15N (heavy) and switch to 14N (light)
Conservative ~ original is preserved and new ones are made
Dispersive ~ mix of old and new DNA
Semiconservative ~ old DNA acts as a template
1 division by centrofusion
Has 1 strand of 15N and 1 strand of 14N

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23
Q

what occurs in Replication?

A

1 strand of DNA is the template strand
Unzips DNA
Uses DNA Helicase powered by ATP
Nucleotides are linked together by covalent bonds

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24
Q

what is Fidelity?

A

The chance on miscopied DNA for base pairs is 1 in 10^6 bp
Proof-reading enzyme
Repair of mismatch DNA enzyme
Lowers overall rate to 10^10 bp

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25
what is Central Dogma?
Information from DNA is utilized to make proteins DNA is transcribed to mRNA and then translated into proteins - DNA is the blueprint for genes
26
what is transcription?
The DNA template is recorded 3 different steps
27
what is translation?
the process by which a cell makes proteins using the genetic information carried in messenger RNA (mRNA). The mRNA is made by copying DNA, and the information it carries tells the cell how to link amino acids together to form proteins.
28
what is the process of translation?
mRNA → amino acids → proteins 20 amino acids Use codons (3 nucleotides) which equal 64 combinations Genetic code is degenerate More than one set of codons code for genes Takes place in the ribosomes Scaffolding mRNA is read (start codon AUG) tRNA has an anticodon that is complementary the codon Then added to the polypeptide chains Creates amino acids Stop codons are UAA, UAG, UGA Once it hits this, polypeptides are released
29
what is a point mutation?
Replace one nucleotide with another
30
what is a silent mutation?
No change in protein Codes of the same amino acid
31
what is a missense mutation?
Results in an amino acid substitution Sometimes no problem but other times it makes a big difference (sickle cell animea) Get valine instead of glutamic acid
32
what is a nonsense mutation?
Substitutes a stop codon for an amino acid Makes the protein shorter so it probably doesn’t work
33
what is a Frameshift mutation?
Add or delete a nucleotide More disastrous than point mutations mRNA is read as a series of nucleotide codons so the reading frame is altered from that point on
34
what is a Spontaneous mutation?
Just happens are a low rate
35
what are mutagens?
Chemical or physical traits that disrupt/change your DNA to cause it mutate
36
what are Transposable Elements?
they make a mess of genes
37
what are SNPs?
Single nucleotide polymorphisms Places where minor changes in base pair take place High in some populations but smaller in others Useful in ancestry study In Iceland decode is a company that has health, genealogy, and DNA sequence from Iceland's population All related to each other (relatively)
38
what is Natural selection?
Process that descents different survival and reproduction of individuals which have different heritable traits
39
who discovered the Adaptation Theory?
Lamark (1809)
40
what is the adaption theory?
Use and disuse of parts Orgaisms have a built in drive towards perfection Inheritance of acquired characteristics Modification during lifetime passed down during generation
41
what does natural selection act upon?
Different phenotypes → different genotypes Natural selection acts on phenotypes
42
what is the cause of natural selection?
Cause of natural selection is abiotic and biotic environment Not on genotype that is good in all situation Depends on current environment Benefits individuals not groups Not for good of species but what is best for the individuals and its genes Natural selection sifts varates from less successful to more successful Selection can change gene frequency (phenotypes)
43
what is a gene pool?
Total of all genes in all individuals in a population
44
what is evolution?
Change in genetic makeup in a population overtime All forms of life are descended with modifications from ancestral species Due to natural selection (a mechanism)
45
what is Rifampin?
Antibiotic that targets a protein in the bacteria (RNA polymerase) then kills the bacteria
46
what is the Hardy-Weinberg Law?
In a sexually reproducing population single generation of random mating results in (produces) stable/constant frequency of alleles and phenotypes
47
what are the 5 requirements of Hardy-Weinberg?
1. Large population 2. No mutations 3. No migration 4. Random mating 5. All genotypes have equal reproductive success - No natural selection
48
what is Stabilizing Selection?
Intermediate phenotype is favored over the extreme Increase the frequency of the average phenotype Reduce genetic variation
49
what is directional selection?
One extreme phenotype is favored over the other Shifts distribution of offspring in one direction
50
what is disruptive selection?
Both extremes phenotypes are favored over the intermediate
51
what is relative fitness?
Survivorship/reproduction of a phenotype compared to the best one in the environment - Mainly uses survivorship
52
What are the characteristics of sickle cell anemia?
- Autosomal recessive disease - SIngle base pair change in hemoglobin (4 chains) causing a change in shape in red blood cells - Missense mutation
53
what is Non-Random Mating?
Organism chooses its type based on ideal phenotype
54
what is Assortative mating?
Mating with similar phenotypes Social, political, religious constraints, which leads to reproductive isolation Leads to recessive genetic disease clustered in a group
55
what is inbreeding?
Mating with individuals that have shared genes which are identical by descent
56
what is Migration?
Gene flow increases or decrease genetic variation Can bring in novel alleles to population (increase genetic variation) Homogenize populations (reduces genetic variation) Gene flow between populations makes them similar
57
what is genetic drift?
Change in allele frequency due to chance Relative fitness of the allele does not matter Important in small populations Random fluctuations in allele frequency can lead to loss of allele by chance
58
what is the Founder Effect?
the reduction in genomic variability that occurs when a small group of individuals becomes separated from a larger population.
59
what can cause increased genetic variation?
Sexual reproduction can increase genetic varaition but cannot change allele frequency Gene flow can increase genetic variation by immigration
60
what can cause decreasing genetic variation?
- Stability selection - Directional selection - Can remove an allele from the population (fixation) - Genetic Drift - Lose alleles - Inbreeding - Reduce heterozygosity but not change allele frequency - Gene flow - Can homogenize populations which prevent new combinations
61
what is Speciation?
Process of splitting one species into several
62
what is Allopatric Speciation?
When a population forms a new species while geographically separated from the parent population Example: Mountain, ocean, pond, roads, etc.
63
what is Prezygotic isolation?
Reduces the probability of a zygote forming Do not cost very much (avoiding species)
64
what are the 5 types of Prezygotic isolation?
1. Habitat Isolation: Leopard frog 2. Temporal Isolation: Mate/flower at different times 3. Behavioral Isolation: Little sex attraction Sometimes mediated by chemicals (pheromones) 4. Mechanical Isolation: Different mating parts 5. Gametic Isolation: Gametes fail to attract each other
65
what is Postzygotic isolation?
Reduces performance of zygote Cost valuable resources (dooming the carrier of genes)
66
what are the 3 types of Postzygotic isolation?
1. Developmental Isolation The embryo does not develop 2. Hybrid Inviability Hybrid adults are weak and die before they can reproduce No gene flow 3. Hybrid Sterility Hybrid does not produce functional gametes Mules (horse x donkey) Liger (lions x tigers)
67
what is Adaptive Radiation?
emergence of (numerous) new species from a common ancestor usually introduced to a new environment
68
what is the difference between allopatric and sympatric speciation?
In allopatric speciation, groups from an ancestral population evolve into separate species due to a period of geographical separation. In sympatric speciation, groups from the same ancestral population evolve into separate species without any geographical separation.
69
what is the Hybrid Zone?
Well-defined geographic area where hybridization occurs

Biology 121 Final Exam (3 decks)

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