UC Davis BIO 001 Midterm 2 Study Guides + Lecture Flashcards

[INHERITANCE] What is the Central Dogma of biology?

DNA → RNA → Protein. Genetic information is transcribed from DNA into RNA and translated into a protein.

[INHERITANCE] What is transcription?

The process of copying DNA information into RNA. It occurs in the nucleus in eukaryotic cells.

[INHERITANCE] What is translation?

The process of using mRNA instructions to assemble amino acids into a protein. It occurs at ribosomes.

[INHERITANCE] What is the product of transcription?

RNA, specifically messenger RNA (mRNA) when describing protein-coding genes.

[INHERITANCE] What is the final product of gene expression?

A protein.

[INHERITANCE] What is an allele?

An alternative version of a gene.

[INHERITANCE] What is a gene?

A section of DNA that contains instructions for a functional product.

[INHERITANCE] What is a genotype?

The genetic makeup or combination of alleles an organism possesses.

[INHERITANCE] What is a phenotype?

The observable characteristics of an organism, influenced by genotype and environment.

[INHERITANCE] What is a locus?

The specific physical location of a gene on a chromosome.

[INHERITANCE] What is a genome?

The complete set of genetic material in an organism.

[INHERITANCE] How many chromosomes are in a human liver cell versus a sperm cell?

46 in a liver cell (diploid); 23 in a sperm cell (haploid).

[INHERITANCE] What is a synonymous mutation?

A DNA mutation that changes a codon but does not change the amino acid produced.

[INHERITANCE] Why might a mutation not cause a phenotypic change?

It may be synonymous or occur in a region that does not contain or regulate genes.

[INHERITANCE] What is wobble pairing?

When multiple codons code for the same amino acid, often because of differences in the third codon position.

[INHERITANCE] Which codon position is most likely to tolerate mutations without changing the amino acid?

The third position, because of wobble pairing.

[INHERITANCE] What is complete dominance?

The heterozygote displays the same phenotype as the homozygous dominant individual.

[INHERITANCE] What is incomplete dominance?

The heterozygote displays an intermediate phenotype between the two homozygotes.

[INHERITANCE] What is codominance?

Both alleles are fully expressed in the heterozygote.

[INHERITANCE] In a codominant trait, what would a heterozygous horse with brown and white spotting demonstrate?

Codominance because both colors are visibly expressed.

[INHERITANCE] What is simple dominance?

One allele masks the expression of another allele in a heterozygote.

[INHERITANCE] What is epistasis?

An interaction in which an allele at one gene affects or masks the expression of another gene.

[INHERITANCE] What is pleiotropy?

When one gene influences multiple phenotypic traits.

[INHERITANCE] What is polygenic inheritance?

When multiple genes contribute to one phenotypic trait.

[INHERITANCE] How does environmental influence on phenotype work?

Environmental conditions affect how a genotype is expressed, producing different phenotypes.

[INHERITANCE] What inheritance pattern explains human eye color being influenced by several genes?

Polygenic inheritance.

[INHERITANCE] What inheritance pattern explains bunny coat color changing with temperature?

Environmental effects on phenotype.

[INHERITANCE] What is a Punnett square used for?

Predicting the possible genotypes and phenotypes of offspring from a genetic cross.

[INHERITANCE] What is a homozygous genotype?

An organism has two identical alleles at a gene, such as AA or aa.

[INHERITANCE] What is a heterozygous genotype?

An organism has two different alleles at a gene, such as Aa.

[INHERITANCE] What is the expected offspring phenotype from RR × rr under complete dominance?

100% dominant phenotype; all offspring have genotype Rr.

[INHERITANCE] What is the expected genotype ratio from Rr × Rr?

1 RR : 2 Rr : 1 rr.

[INHERITANCE] What is the expected phenotype ratio from Rr × Rr under complete dominance?

3 dominant : 1 recessive.

[INHERITANCE] What offspring result from BBtt × bbTT?

100% BbTt, displaying black coats and trotting gait.

[INHERITANCE] A black cat crossed with a gray cat produces 50% black and 50% gray offspring. What is the black parent's genotype?

Bb. The gray parent is bb, so a 1:1 ratio indicates a heterozygous black parent.

[INHERITANCE] What is a test cross?

Crossing an individual with a dominant phenotype with a homozygous recessive individual to determine its genotype.

[INHERITANCE] What does genetic linkage mean?

Genes located close together on the same chromosome tend to be inherited together.

[INHERITANCE] What does a high recombination frequency indicate?

Genes are relatively far apart on the same chromosome, or may be unlinked.

[INHERITANCE] What does a low recombination frequency indicate?

Genes are closely linked on the same chromosome.

[INHERITANCE] What is the probability multiplication rule?

For two independent events occurring together, multiply their probabilities.

[INHERITANCE] What is the probability addition rule?

For mutually exclusive pathways leading to an outcome, add their probabilities.

[INHERITANCE] What is an X-linked trait?

A trait controlled by a gene located on the X chromosome.

[INHERITANCE] Why are X-linked recessive diseases more common in males?

Males have only one X chromosome, so one recessive disease allele can produce the phenotype.

[INHERITANCE] A carrier female for hemophilia (XHXh) has children with a healthy male (XHY). What percentage of sons are expected to have hemophilia?

50% of sons.

[INHERITANCE] What percentage of daughters from XHXh × XHY are expected to have hemophilia?

0%. Daughters receive the healthy XH allele from their father.

[INHERITANCE] If a father has an X-linked disease, what percentage of his sons inherit the affected X chromosome from him?

0%. Fathers pass their Y chromosome to sons and their X chromosome to daughters.

[POPULATION GENETICS] What is population genetics?

The study of genetic variation and allele frequency changes within populations over time.

[POPULATION GENETICS] What is Hardy-Weinberg equilibrium (HWE)?

A condition in which allele and genotype frequencies remain constant across generations when its assumptions are met.

[POPULATION GENETICS] What are the Hardy-Weinberg genotype equations?

p² + 2pq + q² = 1.

[POPULATION GENETICS] What does p represent in Hardy-Weinberg equilibrium?

The frequency of the first allele, usually the dominant allele.

[POPULATION GENETICS] What does q represent in Hardy-Weinberg equilibrium?

The frequency of the second allele, usually the recessive allele.

[POPULATION GENETICS] What is the Hardy-Weinberg allele frequency equation?

p + q = 1.

[POPULATION GENETICS] What are the five assumptions of Hardy-Weinberg equilibrium?

No mutation, no migration (gene flow), no natural selection, random mating, and a very large population (negligible genetic drift).

[POPULATION GENETICS] Does genotype frequency adding up to 1 automatically prove HWE?

No. Genotype frequencies must also match the expected Hardy-Weinberg frequencies.

[POPULATION GENETICS] Why is HWE useful?

It provides a baseline to determine whether a population is evolving and helps identify possible evolutionary processes.

[POPULATION GENETICS] How do you calculate allele frequencies from genotype frequencies?

p = f(AA) + ½f(Aa); q = f(aa) + ½f(Aa).

[POPULATION GENETICS] If p = 0.7, what is q?

0.3, because p + q = 1.

[POPULATION GENETICS] If p = 0.7 and q = 0.3, what is the expected heterozygote frequency?

2pq = 2(0.7)(0.3) = 0.42 or 42%.

[POPULATION GENETICS] If p² = 0.46, what is p?

p = √0.46 ≈ 0.68.

[POPULATION GENETICS] If p = 0.8, what is q²?

q = 0.2, so q² = 0.04 or 4%.

[POPULATION GENETICS] If the recessive phenotype occurs in 9% of a population in HWE, what is q?

q = √0.09 = 0.3.

[POPULATION GENETICS] What is natural selection?

A nonrandom evolutionary process in which individuals with advantageous heritable traits have greater reproductive success.

[POPULATION GENETICS] What is genetic drift?

Random changes in allele frequencies caused by chance events.

[POPULATION GENETICS] When is genetic drift strongest?

In small populations, where chance events have larger effects on allele frequencies.

[POPULATION GENETICS] What is gene flow?

The movement of alleles between populations through migration and reproduction.

[POPULATION GENETICS] What happens to two populations when gene flow increases?

They generally become more genetically similar.

[POPULATION GENETICS] What is mutation's role in evolution?

Mutations create new genetic variants and can introduce new alleles into populations.

[POPULATION GENETICS] What is nonrandom mating?

Mating that is not random with respect to genotype or phenotype; it can change genotype frequencies.

[POPULATION GENETICS] Does nonrandom mating necessarily change allele frequencies?

No. It can change genotype frequencies without necessarily changing allele frequencies.

[POPULATION GENETICS] What is the founder effect?

Genetic drift that occurs when a new population is established by a small number of individuals.

[POPULATION GENETICS] What is a population bottleneck?

A sharp reduction in population size that causes loss of genetic variation through drift.

[POPULATION GENETICS] How are the founder effect and bottleneck similar?

Both involve small populations and random changes in allele frequencies that can reduce genetic diversity.

[POPULATION GENETICS] What is fixation?

When an allele reaches a frequency of 1.0 and is the only allele remaining at that locus in the population.

[POPULATION GENETICS] What is non-adaptive evolution?

Evolutionary change that occurs without necessarily improving fitness, such as genetic drift and gene flow.

[POPULATION GENETICS] What is adaptive evolution?

Evolutionary change caused by natural selection favoring heritable traits that improve reproductive success in a particular environment.

[POPULATION GENETICS] What is heterozygote advantage?

When heterozygous individuals have greater fitness than either homozygous genotype.

[POPULATION GENETICS] Why can the sickle-cell heterozygote be favored in malaria regions?

Ss individuals have increased malaria resistance without the severe effects associated with ss individuals.

[POPULATION GENETICS] Why can a beneficial recessive allele take longer to reach fixation?

When rare, it is mostly hidden in heterozygotes, so natural selection cannot easily favor it.

[POPULATION GENETICS] What is the relationship between allele frequency and evolution?

A change in allele frequencies across generations is evolution at the population level.

[COMMUNITY ECOLOGY] What is community ecology?

The study of interactions among different species living in the same community.

[COMMUNITY ECOLOGY] What do the signs +, −, and 0 represent in species interactions?

Positive = benefits; negative = harmed; zero = no significant effect.

[COMMUNITY ECOLOGY] What is competition?

A −/− interaction in which both species are negatively affected because they share limiting resources.

[COMMUNITY ECOLOGY] What is exploitation?

A +/− interaction in which one species benefits while another is harmed.

[COMMUNITY ECOLOGY] What are three examples of exploitation?

Predation, herbivory, and parasitism.

[COMMUNITY ECOLOGY] What is mutualism?

A +/+ interaction in which both species benefit.

[COMMUNITY ECOLOGY] What is commensalism?

A +/0 interaction in which one species benefits and the other is unaffected.

[COMMUNITY ECOLOGY] What is amensalism?

A −/0 interaction in which one species is harmed and the other is unaffected.

[COMMUNITY ECOLOGY] What is neutralism?

A 0/0 interaction in which neither species is significantly affected.

[COMMUNITY ECOLOGY] What is symbiosis?

A close, often long-term relationship between two different species.

[COMMUNITY ECOLOGY] What is facilitation?

An interaction in which one or both species benefit and neither is harmed.

[COMMUNITY ECOLOGY] What is an obligate interaction?

An interaction that a species requires to survive or complete its life cycle.

[COMMUNITY ECOLOGY] What is a facultative interaction?

An interaction that benefits a species but is not required for its survival.

[COMMUNITY ECOLOGY] What is a fundamental niche?

The full range of environmental conditions and resources in which a species can survive and reproduce.

[COMMUNITY ECOLOGY] What is a realized niche?

The part of a species' potential niche that it actually occupies after interactions, dispersal, and history are considered.

[COMMUNITY ECOLOGY] How do competitors affect a species' realized niche?

They can shrink it by preventing the species from using certain resources or environmental conditions.

[COMMUNITY ECOLOGY] How do mutualists affect a species' realized niche?

They can expand it by helping the species access additional resources or conditions.

[COMMUNITY ECOLOGY] What is a food chain?

A linear sequence showing how energy moves from one organism to another.

[COMMUNITY ECOLOGY] What is a food web?

A network of interconnected food chains showing feeding relationships in a community.