2nd Semester Biology Comprehensive Review

Comprehensive flashcards covering DNA structure, protein synthesis, cell division, genetics, evolution, and ecology based on the semester review transcript.

Who determined the double helix structure of DNA?

James Watson and Francis Crick are primarily credited, alongside contributions from Rosalind Franklin.

What makes up a DNA nucleotide?

A DNA nucleotide consists of a sugar (deoxyribose), a phosphate group, and a nitrogenous base.

What type of bonds are in DNA?

Hydrogen bonds link nitrogenous bases, while covalent bonds connect the sugar-phosphate backbone.

What does 'semi-conservative' replication mean?

In semi-conservative replication, each new DNA molecule has one original strand and one new strand.

Name the main enzymes in DNA replication.

DNA helicase unwinds DNA; DNA polymerase synthesizes new DNA strands.

What is a karyotype?

A karyotype visually represents the complete set of chromosomes in a cell.

Karyotype for Down syndrome?

An individual with Down syndrome has three copies of chromosome 21 (Trisomy 21).

How many amino acids from 300 nucleotides?

300 nucleotides yield 100 amino acids, as each amino acid is coded by a triplet (3 nucleotides).

Define a frameshift mutation.

A frameshift mutation occurs from the insertion or deletion of nucleotides, altering the reading frame.

Chromatin vs. chromosomes?

Chromatin is loose DNA during Interphase; chromosomes are tightly coiled during Mitosis.

Mitosis yields what cell type?

Mitosis produces two identical diploid ($2n$) somatic cells.

What does meiosis produce?

Meiosis results in four genetically unique haploid ($n$) gametes.

Purpose of crossing over in meiosis?

Crossing over increases genetic diversity by exchanging segments between homologous chromosomes.

Chromosome count in human cells?

Somatic cells have $46$ chromosomes; gametes contain $23$ chromosomes.

What does homozygous mean?

Homozygous indicates two identical alleles for a gene (e.g., $AA$ or $aa$).

What is heterozygous?

Heterozygous refers to having two different alleles for a gene (e.g., $Aa$).

Child’s blood type probability of B from $I^Bi$ and $I^AI^B$?

The probability is $50\\%$; potential genotypes are $I^BI^B$ or $I^Bi$.

Hemophilia probability in female offspring from carrier mother?

There is a $0\\%$ chance of a hemophiliac female since she receives a dominant $X^H$ from her father.

Variation vs. adaptation?

Variation is genetic diversity, while adaptation is a beneficial variation promoting survival.

Artificial selection vs. natural selection?

Artificial selection is human-driven breeding; natural selection is environment-driven trait selection.

What are vestigial structures?

Vestigial structures are evolutionary remnants of once-functional organs (e.g., tailbone in humans).

What is convergent evolution?

Convergent evolution occurs when unrelated species develop similar traits due to similar environments.

Conditions for Hardy-Weinberg equilibrium?

Conditions include a large population, no gene flow, no mutations, random mating, and no natural selection.

Bottleneck effect vs. founder effect?

Bottleneck occurs from dramatic size reduction due to an event; founder effect is a small group's isolation.

Difference between primary and secondary succession?

Primary succession starts on bare rock; secondary succession occurs in areas after disturbances, with soil present.

What is the mark-recapture method estimate?

Using marks, if $50$ eels are marked and $400$ caught with $10$ marked, the estimated population is $2000$.

Example symbiotic relationships.

(a) Goby fish and shrimp: Mutualism. (b) Remoras and sharks: Commensalism.