Semester 2 Biology Study Guide Flashcards

These vocabulary flashcards cover key concepts from the Semester 2 Biology Study Guide, including DNA replication, protein synthesis, mutations, cell division, inheritance, viruses, the cell cycle, and ecology.

Helicase

Unwinds double stranded DNA helix by breaking hydrogen bonds.

Primase

Lays down a short RNA primer to give DNA polymerase a starting point to build.

DNA Polymerase

Adds DNA nucleotides to the growing strand and proofreads the new strand.

Gene

A segment of DNA that contains the code to build protein.

Nucleotide

The building block of DNA consisting of a Phosphate, a Nitrogen base, and a Deoxyribose sugar.

Transcription

The process where DNA is copied into mRNA; occurs in the nucleus.

Translation

The process where mRNA is made into a protein; occurs in the cytoplasm and ribosome.

Codon

A sequence of $3$ nucleotides found in DNA and RNA.

Mutation

An error in DNA that causes a change.

Silent Mutation

A mutation that changes a nucleotide but results in the same amino acid sequence.

Missense Mutation

A mutation that changes the DNA sequence such that a different amino acid is produced.

Nonsense Mutation

A mutation that results in a premature stop codon, ending the protein translation early.

Frameshift Mutation

A mutation caused by the insertion or deletion of a nucleotide, shifting the reading frame of the genetic message.

Haploid

Cells produced in meiosis that contain only one set of chromosomes; represented as $y$ or $n$.

Diploid

Cells produced in mitosis that contain two complete sets of chromosomes; represented as $Z$ or $2n$. For example, an emperor penguin body cell has $72$ chromosomes.

Gametes

Haploid sex cells produced by meiosis, such as sperm and egg cells.

Somatic cells

Diploid body cells produced by mitosis.

Prophase I

A stage of meiosis where the nuclear membrane disappears, chromatin thickens into chromosomes, spindle fibers form, and homologous chromosomes pair up to exchange DNA.

Metaphase I

The stage of meiosis where homologous chromosomes line up in the middle of the cell.

Anaphase I

The stage of meiosis where homologous chromosomes move away from each other toward opposite poles.

Genotype

The genetic representation of a trait, such as $Ss$ or $ss$.

Phenotype

The physical characteristics of an organism, such as shorthair or longhair.

Codominance

An inheritance pattern where both alleles are expressed, such as blood type $AB$ (genotype $I^A I^B$).

Capsid

The protein shell of a virus that contains DNA or RNA.

Lytic Cycle

A viral reproductive cycle where the virus injects its DNA and hijacks the host cell to replicate the virus.

Lysogenic Cycle

A viral reproductive cycle where viral DNA integrates into the host cell's genome.

Zone of Inhibition

The area around an antiseptic where bacterial growth is stopped; a smaller zone indicates the antiseptic is less effective.

Interphase

The phase of the cell cycle where DNA replicates, the cell grows, and normal metabolic functions occur.

HeLa cells

Immortal cell lines derived from Henrietta Lacks that can divide indefinitely.

Contact Inhibition

A property of normal cells to stop dividing when they touch neighboring cells; cancer cells ignore this and pile up.

p53

A protein in normal cells that fixes DNA damage or triggers apoptosis; in cancer cells, it is mutated or nonfunctional.

Ecological Isolation

An isolation mechanism that impedes the meeting of potential pairs because they live in different habitats.

Temporal Isolation

A mechanism where species breed at different times of the year.

Behavioral Isolation

Isolation between populations due to differences in courtship or mating signals, such as mating songs.

Mechanical Isolation

Isolation due to structural differences, such as snails whose genitals cannot align properly because of differently spiraled shells.

HIPPO

An acronym for threats to biodiversity: Habitat destruction, Invasive species, Population growth, Pollution, and Over-consumption.