AP BIO – 150 DETAILED FLASHCARDS

What is autosomal dominant inheritance?

Autosomal dominant inheritance appears every generation and affected individuals have affected parents.

What is autosomal recessive inheritance?

Autosomal recessive inheritance skips generations, affected individuals can have unaffected parents, and males and females are equally affected.

What is X-linked recessive inheritance?

X-linked recessive inheritance occurs when a gene is located on the X chromosome, and males are more likely to express the trait because they only have one X chromosome.

no father to son transmission

affected sons have carrier mothers

affected fathers —> all daughters

What is a carrier in genetics?

A carrier is an individual who has one recessive allele for a trait but does not show the phenotype because they also have a dominant allele.

What is the law of segregation?

The law of segregation states that allele pairs separate during gamete formation, so each gamete carries only one allele for each gene.

What is the law of independent assortment?

The law of independent assortment states that genes for different traits are inherited independently of one another if they are on different chromosomes. Happens because homologous chromosome pairs line up randomly in metaphase 1.

What does homozygous mean?

Homozygous refers to having two identical alleles for a gene, such as AA or aa.

What does heterozygous mean?

Heterozygous refers to having two different alleles for a gene, such as Aa.

What does the equation p² + 2pq + q² = 1 represent?

This equation represents the frequencies of genotypes in a population, where p² is homozygous dominant, 2pq is heterozygous, and q² is homozygous recessive.

What does p represent?

The variable p represents the frequency of the dominant allele in the population.

What does q represent?

The variable q represents the frequency of the recessive allele in the population.

What happens during reception?

a signaling molecule called a ligand binds to a specific receptor protein, causing the receptor to change shape.

What happens during transduction?

the signal is passed along through a series of proteins in a cascade, often involving phosphorylation reactions.

What happens during the response stage?

the cell carries out a specific action, such as turning on a gene or activating an enzyme.

What is a ligand?

a signaling molecule that specifically binds to a receptor protein to initiate a cellular response.

What is signal amplification?

occurs when one ligand-receptor interaction activates multiple molecules in a cascade, greatly increasing the strength of the response.

What is insulin?

a hormone released by the pancreas that helps lower blood glucose levels by allowing cells to take in glucose.

What happens when insulin binds to its receptor?

it activates a signaling cascade that results in glucose transport proteins moving to the cell membrane.

What is the result of insulin signaling?

glucose enters the cell, lowering the concentration of glucose in the bloodstream.

What is passive transport?

the passive movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached.

What is osmosis?

the diffusion of water across a selectively permeable membrane toward the side with a higher solute concentration.

What is facilitated diffusion?

the passive movement of molecules across a membrane with the help of transport proteins.

What is active transport?

the movement of substances against their concentration gradient using energy in the form of ATP. low to high

What happens in a hypertonic solution?

higher solute concentration (inside the cell), making water leave the cell, causing the cell to shrink.

What happens in a hypotonic solution?

less solute concentration, (more water concentration) water enters the cell, causing it to swell and possibly burst.

What happens in an isotonic solution?

water moves equally in and out of the cell, so there is no net change in cell size.

What is an enzyme?

a biological catalyst that speeds up chemical reactions by lowering the activation energy required.

How do enzymes work step-by-step?

First, the substrate binds to the enzyme’s active site; then the enzyme changes shape slightly (induced fit), the reaction occurs, products are released, and the enzyme remains unchanged.

What is activation energy?

the minimum amount of energy required to start a chemical reaction.

What is denaturation?

occurs when an enzyme loses its 3D shape due to extreme conditions, causing it to stop functioning.

What happens during G1 phase?

the cell grows physically larger, copies organelles, and produces the proteins and molecular building blocks (happens directly after mitosis)

What happens during S phase?

the cell replicates its DNA, ensuring each daughter cell receives an identical set of chromosomes.

What happens during G2 phase?

rapid cell growth and protein synthesis during which the cell prepares itself for mitosis.

What happens in prophase?

chromosomes condense, the nuclear envelope breaks down, and the spindle apparatus begins to form.

What happens in metaphase?

chromosomes line up along the center of the cell, known as the metaphase plate.

What happens in anaphase?

sister chromatids are pulled apart toward opposite poles of the cell.

What happens in telophase?

two new nuclei form and chromosomes begin to decondense.

What is cytokinesis?

the division of the cytoplasm, resulting in two identical daughter cells.

What happens during transcription?

process of copying a segment of DNA into RNA (specifically mRNA) by the enzyme RNA polymerase to enable gene expression

What happens during translation?

Ribosomes read codons on mRNA, tRNA brings the correct amino acids, and peptide bonds form to create a protein.

What is natural selection?

the process where individuals with advantageous traits are more likely to survive and reproduce, passing those traits on.

What is genetic drift?

a random change in allele frequencies, especially in small populations.

What stage of the cell cycle is DNA replicated?

S phase of interphase, ensuring that each daughter cell receives an identical set of genetic information.

During which stage do chromosomes line up in the middle of the cell?

metaphase, forming what is known as the metaphase plate.

During which stage are sister chromatids pulled apart?

anaphase.

What is gene flow?

the movement of alleles between populations through migration, which can increase genetic diversity.

What is genetic variation?

the diversity in DNA sequences among individuals within a population, arising from mutations, gene flow, and sexual reproduction

What is a mutation?

A mutation is a change in the DNA sequence that can affect gene expression and protein function.

What is phosphorylation?

the addition of a phosphate group to a protein, which often activates or changes the function of that protein.

What is ATP used for in cells?

used as an energy source to power cellular processes such as active transport, muscle contraction, and chemical reactions.

What is enzyme specificity?

the ability of an enzyme to bind only to a specific substrate due to the shape of its active site.

What is equilibrium in diffusion?

the point at which molecules are evenly distributed and there is no net movement of substances across a membrane.

What is the role of RNA polymerase in transcription?

RNA polymerase binds to DNA and synthesizes an mRNA strand by adding complementary RNA nucleotides.

What is the function of tRNA in translation?

carries specific amino acids to the ribosome and matches its anticodon with the codon on mRNA.

What is a codon?

A codon is a sequence of three nucleotides on mRNA that codes for a specific amino acid.

What happens during a frameshift mutation?

occurs when nucleotides are inserted or deleted, shifting the reading frame and altering the entire protein sequence.

What is the bottleneck effect?

a type of genetic drift that occurs when a population is drastically reduced in size, leading to a loss of genetic diversity.

What are trophic levels?

the different feeding positions in a food chain, such as producers, primary consumers, and secondary consumers.

What is the 10% rule?

The 10% rule states that only about 10% of energy is transferred from one trophic level to the next.

What is an exergonic reaction?

An exergonic reaction releases energy, and the products have less energy than the reactants. Ex. cellular respiration, ATP hydrolysis

What is an endergonic reaction?

An endergonic reaction requires an input of energy, and the products have more energy than the reactants. Ex.Photosynthesis, DNA replication, dehydration synthesis

What is meant by "semiconservative replication"?

that each new DNA molecule contains one original parental strand and one newly synthesized strand, which ensures accurate copying using the original strand as a template.

Why must DNA be replicated before cell division?

DNA must be replicated so that each daughter cell receives a complete and identical set of genetic instructions necessary for survival and function.

What is the role of the template strand in replication?

The template strand provides the sequence that determines the order of nucleotides added to the new strand through complementary base pairing.

Why can DNA only be synthesized in the 5′ → 3′ direction?

DNA polymerase can only add nucleotides to the 3′ end of a growing strand, which forces all new DNA synthesis to occur in the 5′ to 3′ direction.

What does it mean that DNA strands are antiparallel?

Antiparallel means one DNA strand runs 5′ → 3′ while the other runs 3′ → 5′, which creates challenges during replication.

Why does antiparallel structure complicate replication?

Because DNA polymerase only works 5′ → 3′, one strand can be copied continuously while the other must be copied in fragments.

What is a replication fork?

the Y-shaped region where the DNA double helix is unwound and new strands are being synthesized.

What does helicase do?

Helicase unwinds the DNA double helix by breaking hydrogen bonds between base pairs, allowing replication to begin.

What is the role of topoisomerase?

enzymes that regulate DNA topology by breaking, rearranging, and resealing DNA strands to relieve torsional strain, prevent tangling, and manage supercoiling during replication, transcription, and repair.

Why is topoisomerase essential?

Without topoisomerase, DNA would become tightly coiled and replication would stall due to mechanical stress.

What does primase (RNA polymerase) do?

synthesizes short RNA primers that provide a starting point for DNA polymerase to begin adding nucleotides.

Why can DNA polymerase not start replication on its own?

requires a free 3′ OH group to add nucleotides, which is provided by the RNA primer.

What does DNA ligase do?

DNA ligase joins Okazaki fragments together by forming phosphodiester bonds in the sugar-phosphate backbone.

What is the leading strand?

synthesized continuously in the same direction as the replication fork because it runs 3′ → 5′ as a template.

What is the lagging strand?

synthesized discontinuously in short segments because it runs in the opposite direction of the replication fork. 5 to 3

What are Okazaki fragments?

short segments of DNA synthesized on the lagging strand that are later joined together.

Why are mutations important for evolution?

Mutations provide genetic variation, which is the raw material for natural selection.

What is gene expression?

the process by which information in DNA is used to produce RNA and proteins that determine traits.

Why is gene expression regulation important?

Regulation allows cells with the same DNA to produce different proteins, leading to specialized cell functions.

What is a promoter?

a DNA sequence where RNA polymerase and transcription factors bind to initiate transcription.

What are transcription factors?

proteins that regulate gene expression by increasing or decreasing transcription.

What is positive gene regulation?

occurs when activator proteins increase transcription by helping RNA polymerase bind.

What is negative gene regulation?

occurs when repressors block transcription by preventing RNA polymerase from binding.

What is an enhancer?

a DNA sequence that increases transcription and can be located far from the gene.

What is a silencer?

a DNA sequence that decreases transcription when bound by repressors.

What is differential gene expression?

occurs when different cells express different genes, leading to specialization.

Why do cells with the same DNA become different?

because they turn on different sets of genes, producing different proteins.

What is microRNA (miRNA)?

miRNA is a small RNA molecule that binds to mRNA and prevents it from being translated or causes it to degrade.

What is the effect of miRNA on protein production?

miRNA decreases protein production by blocking translation or degrading mRNA.

How does a DNA mutation affect phenotype?

A mutation can change the mRNA sequence, which may alter the amino acid sequence, affecting protein structure and function and ultimately the phenotype.

What happens during initiation of translation?

The ribosome binds to mRNA, the start codon is recognized, and the first tRNA attaches.

What happens during elongation?

tRNA brings amino acids, peptide bonds form, and the ribosome moves along the mRNA.

What happens during termination?

A stop codon is reached, and the completed protein is released.

What is a silent mutation?

A silent mutation does not change the amino acid due to redundancy in the genetic code.

What is a missense mutation?

A missense mutation changes one amino acid, potentially affecting protein function.

What is a nonsense mutation?

A nonsense mutation creates a stop codon, leading to a shortened protein.

What is a frameshift mutation?

A frameshift mutation shifts the reading frame, altering all downstream amino acids.

How does DNA replication connect to evolution?

Errors in DNA replication create mutations, which introduce genetic variation that natural selection can act on.

Why is genetic variation necessary for natural selection?

Without variation, all individuals would be identical, and no traits could be selected for or against.