Comprehensive ANTH 1001 Evolution, Genetics, and Cell Biology Flashcards

What was Lamarck's theory?

Use strengthens and disuse weakens organs; acquired changes are inherited.

Who said species were fixed and unchanging?

Carolus Linnaeus.

What was Cuvier's catastrophism?

Sudden disasters cause geological change and extinctions, followed by repopulation.

What was Hutton and Lyell's uniformitarianism?

Processes acting today also acted in the past; this implied an old Earth with time for gradual change.

What did Malthus contribute?

Populations can grow faster than limited food supplies, creating competition.

What did Darwin propose and publish?

Natural selection and common descent; On the Origin of Species (1859).

Who independently developed natural selection?

Alfred Russel Wallace.

Lamarck versus Darwin: where does change occur?

Lamarck: an individual changes during life and passes acquired traits on. Darwin: inherited variation already exists; trait frequencies change across generations.

What are Darwin's four linked points?

High reproductive potential despite often stable population size; limited resources and competition; variation among individuals; advantageous inherited traits increase through differential reproduction.

What does natural selection act on, and what evolves?

Selection acts on individual phenotypes; populations evolve as allele frequencies change across generations.

What is a gene?

A DNA sequence associated with making a product, such as a protein.

What is an allele?

An alternative form of a gene, such as R or w.

Genotype versus phenotype?

Genotype is an allele combination (Rw); phenotype is the observable trait (round).

Homozygous versus heterozygous?

Homozygous: same alleles (RR or ww). Heterozygous: different alleles (Rw).

Dominant versus recessive?

A dominant allele shows in a heterozygote; a recessive phenotype requires two recessive copies in this simple model.

What is the law of segregation?

The two alleles for a gene separate during gamete production, so each gamete gets one.

What is independent assortment?

In the simplified unlinked-gene model, inheritance of one trait does not affect another.

Rw × Rw: genotype and phenotype ratios?

1 RR : 2 Rw : 1 ww; 3 round : 1 wrinkled (if R is dominant).

Rw × Rw: offspring percentages?

25% RR, 50% Rw, 25% ww; 75% dominant phenotype, 25% recessive.

Yg × gg: what are the offspring?

50% Yg (yellow), 50% gg (green); both ratios are 1:1.

What gametes can Rw,Ts produce?

RT, Rs, wT, ws.

Two Rw,Ts parents: phenotype ratio?

9 round/tall : 3 round/short : 3 wrinkled/tall : 1 wrinkled/short.

Why can there be more genotypes than phenotypes?

Different genotypes can produce the same visible trait.

What are homologous chromosomes?

One maternal and one paternal chromosome with the same gene locations, potentially different alleles.

What are sister chromatids and a centromere?

Replication makes two identical chromatids, temporarily joined at the centromere.

Diploid versus haploid in humans?

Diploid: 46 chromosomes; haploid: 23.

Mitosis: purpose and result?

Growth and maintenance in somatic cells; one division makes two genetically identical diploid cells.

Meiosis: purpose and result?

Gamete production in germ-line cells; two divisions make four genetically different haploid cells.

What happens in interphase?

Genes are active; DNA replicates before division.

What happens in mitotic prophase and metaphase?

Chromosomes condense; then align at the cell center.

What happens in mitotic anaphase and telophase?

Centromeres divide and sister chromatids separate; cytokinesis produces two cells.

What happens in prophase I?

Synapsis pairs homologs; crossing-over exchanges DNA between them.

What happens in metaphase I?

Homologous pairs align, with different pairs orienting independently.

What separates in anaphase I?

Homologous chromosomes; centromeres do not divide and sisters stay together.

Does DNA replicate between meiosis I and II?

No.

What forms after meiosis II?

Four genetically different haploid cells.

What happens in metaphase II and anaphase II?

Chromosomes align in each cell; centromeres divide and sister chromatids separate.

What are two major sources of variation in meiosis?

Crossing-over in prophase I and independent orientation of homologous pairs in metaphase I.

What is DNA made of?

A double helix of nucleotides; each has a phosphate, deoxyribose sugar, and nitrogenous base.

Which DNA bases pair?

A with T; C with G.

What does semiconservative replication mean?

Each copied DNA molecule has one old strand and one new strand.

Replication, transcription, translation: what does each make?

Replication: DNA from DNA; transcription: mRNA from DNA; translation: polypeptide from mRNA.

DNA versus mRNA: three differences?

DNA is double-stranded, uses deoxyribose and T; mRNA is single-stranded, uses ribose and U.

Where do these processes occur in the guide's model?

Replication and transcription in the nucleus; translation at ribosomes in cytoplasm.

Which RNA bases pair?

A with U; C with G.

What is a codon?

A three-base sequence that specifies an amino acid (or a translation signal).

Why is the genetic code redundant?

There are 64 codons but only 20 amino acids; multiple codons can specify one amino acid.

How many three-base codons are possible?

4³ = 64.

What does tRNA do?

Carries an amino acid; its anticodon pairs with a complementary mRNA codon.

Translate AUG UCA AAU.

Methionine - serine - asparagine.

Structural versus regulatory genes?

Structural genes code for products such as hemoglobin; regulatory genes control when other genes switch on or off.

Why can regulatory changes matter greatly?

Altered gene timing or expression can produce major anatomical differences even when many protein sequences are similar.

What is a mutation?

A random change in a gene or chromosome that may be neutral, helpful, or harmful.

What is the ultimate source of new alleles?

Mutation; selection influences whether heritable variants spread.

Why does a mutation's effect depend on environment?

The same expressed change can affect survival or reproduction differently under different conditions.

Which mutations can be inherited by offspring?

Mutations in sex cells or their precursors.

Name three scales of mutation.

Point mutation, chromosomal rearrangement, chromosome-number imbalance.

What is a point mutation?

A change in one nucleotide that may leave protein unchanged or affect function.

What is chromosomal rearrangement?

A segment changes position or arrangement, potentially changing gene expression.

What is chromosome-number imbalance?

Gain or loss of chromosomes, often with larger phenotypic effects.

How can a point mutation be silent?

A changed codon can specify the same amino acid due to redundancy.

Can an amino-acid change be neutral?

Yes, if it has no important functional effect.

What example illustrates environmentally dependent effects?

Sickle-cell hemoglobin.

What mutation rate estimate does the guide give?

About 1 × 10⁻⁵ per gene per cell generation.

Why is mutation alone insufficient to explain much evolutionary change?

Its rate is low; it supplies variation on which other forces act.

What estimate does the guide give for point mutations relative to parents?

About 36% of humans have at least one point mutation.

How does mutation scale generally relate to effects?

Larger-scale changes generally have a greater chance and magnitude of phenotypic effect.

Does dominant mean common, beneficial, or favored?

No, dominance describes expression in heterozygotes; frequency and fitness depend on evolutionary forces.

What is discontinuous variation?

A few distinct categories; example: ABO blood groups.

What is continuous variation?

Many graded values, often involving multiple genes; example: human height.

What is polygeny?

Two or more genes contribute to one trait.

How many genotypes at one diploid locus with a alleles?

a(a + 1)/2.

One locus with two alleles: how many genotypes?

3: RR, Rw, ww.

How many genotypes across G independently considered genes, each with a alleles?

[a(a + 1)/2]^G.

ABO locus with three alleles: how many genotypes?

3² = 9.

Two genes, each with two alleles: how many genotypes?

6: AA, BB, OO, AO, BO, AB.

Ten genes, each with two alleles: how many genotypes?

3¹⁰ = 59,049.

Why is genotypic variation often greater than phenotypic variation?

Dominance and interactions with the environment allow multiple genotypes to yield the same phenotype.

What is heritability?

The share of phenotypic variation in a population attributable to genetic variation.

What is the guide's simple heritability model?

P = G + E; heritability is G/P.

Does heritability say what fraction of one person's trait is genetic?

No, it describes variation in a specific population and environment.

Why does higher heritability help selection act?

Offspring are more likely to resemble parents for the selected trait.

What is a population?

A community within which mating occurs.

What is a gene pool?

All genes and alleles in a breeding population.

What is allele frequency?

The proportion of a particular allele among all alleles at its locus.

What is microevolution versus macroevolution?

Microevolution: allele-frequency change between generations; macroevolution: speciation across many generations.

What are the five assumptions of Hardy-Weinberg equilibrium?

Random mating; infinitely large population; no migration; no mutation; no natural selection.

What does Hardy-Weinberg equilibrium predict?

With all assumptions met, allele and genotype frequencies remain constant across generations.

What does p + q = 1 mean?

Frequencies of the two alleles A (p) and a (q) add to 1.

What does p² + 2pq + q² = 1 mean?

Expected genotype frequencies: AA = p², Aa = 2pq, aa = q².

If q = 0.40, find p, AA, Aa, and aa.

p = 0.60; p² = 0.36; 2pq = 0.48; q² = 0.16.

If the recessive phenotype has frequency 0.16, what is q?

q² = 0.16, so q = 0.40.

If q² = 0.09, find q, p, p², and 2pq.

q = 0.30; p = 0.70; p² = 0.49; 2pq = 0.42.

What does genetic drift do?

In a finite population, it can change allele and genotype frequencies.

What does nonrandom mating alone change?

Genotype frequencies, but not allele frequencies by itself.

What do migration, mutation, and natural selection do to allele frequencies?

Each can change them and thus cause evolution.

What does positive assortative mating or inbreeding do?

Similar individuals mate; homozygosity rises and heterozygosity falls.

What does negative assortative mating or outbreeding do?

Dissimilar individuals mate; homozygosity falls and heterozygosity rises.

What is the full course sequence?

DNA → mutation creates alleles → meiosis reshuffles alleles → fertilization produces genotypes → genotype plus environment influences phenotype → selection changes reproductive success → allele frequencies change.

Which meiotic stage pairs or exchanges homologs?

Prophase I.