Untitled Flashcards Set

Interphase

The phase of the cell cycle where DNA exists as chromatin and the cell prepares for mitosis.

Prophase

The stage of mitosis where chromatin condenses into sister chromatids, the nuclear envelope breaks down, and the mitotic spindle begins to form.

Prometaphase

Stage in mitosis where fragments of the nuclear envelope appear and spindle microtubules attach to chromosomes.

Metaphase

Stage of mitosis where replicated chromosomes line up at the center of the cell.

Anaphase

The phase of mitosis where sister chromatids are pulled apart and move to opposite poles.

Telophase

Stage in mitosis where the nuclear membrane forms around each set of chromosomes, and chromosomes begin to decondense.

Cytokinesis

The process following mitosis where the cell membrane pinches in, leading to the formation of two daughter cells.

Chromatin

A complex of DNA and proteins held together; exists in a loosely packed form during interphase.

Chromosomes

Structures made of chromatin; they consist of two sister chromatids during cell division.

Cell Plate Formation

Cytokinesis in plant cells where vesicles fuse to form a cell plate creating a new cell wall.

Cleavage Furrow Formation

Cytokinesis in animal cells where actin filaments contract to pinch the cell into two daughter cells.

Cell Cycle Checkpoints

Regulatory points in the cell cycle (G1 and G2) that ensure proper DNA replication and readiness for division.

Hayflick Limit

The number of times a normal somatic human cell can divide before cell division stops, approximately 50 divisions.

Cancer

A condition characterized by uncontrolled cell division that can metastasize to other locations in the body.

Mitotic Spindle

A structure made of microtubules that arranges and separates chromosomes during mitosis.

Mitosis

The process of cell division resulting in two identical daughter cells from a single parent cell.

Nondisjunction

Failure of chromosomes to separate properly during cell division, leading to an abnormal number of chromosomes in gametes.

Aneuploidy

A condition where an individual has an abnormal number of chromosomes due to nondisjunction.

Karyotype

A profile of an individual's chromosomes, arranged by size, shape, and number, used to detect chromosomal abnormalities.

Polyploidy

Condition in which cells have more than two complete sets of chromosomes, often seen in plants.

Transcription

The process of copying DNA into mRNA in the nucleus.

Translation

The process of synthesizing proteins from mRNA at the ribosome.

Codon

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

Anticodon

A sequence of three tRNA nucleotides that are complementary to an mRNA codon.

Point Mutation

A DNA mutation that involves a change in a single nucleotide pair.

Frameshift Mutation

A genetic mutation caused by insertions or deletions of nucleotides that alters the reading frame.

Genotype

The genetic composition of an individual, represented by alleles (e.g., AA, Aa, aa).

Phenotype

The observable characteristics of an individual, influenced by the genotype.

Homozygous

An individual with two identical alleles for a particular gene.

Heterozygous

An individual with two different alleles for a particular gene.

Test Cross

A method to determine the genotype of an individual showing a dominant phenotype by crossing with a homozygous recessive individual.

Dihybrid Cross

A genetic cross involving two traits, represented by a 16 grid Punnett square.

Operon

A cluster of functionally related genes that are regulated together, can be either repressible or inducible.

Repressible Operon

An operon that is usually active but can be turned off by a corepressor.

Inducible Operon

An operon that is usually inactive but can be turned on by the presence of an inducer.

Epigenetics

The study of heritable changes in gene expression that do not involve changes to the underlying DNA sequence.

Methylation

The addition of a methyl group to DNA, which can repress gene expression.

Acetylation

The addition of an acetyl group to histone proteins, promoting gene expression by loosening DNA interaction.

RNA Interference

A biological process in which RNA molecules inhibit gene expression by causing the degradation of specific mRNA molecules.

Transgenic Organism

An organism that contains a gene or genes which have been artificially inserted instead of the organism acquiring them through reproduction.

Gene Cloning

The process of making copies of a specific gene or DNA segment by inserting it into plasmids.

PCR (Polymerase Chain Reaction)

A technique used to amplify small segments of DNA for analysis.

Reverse Transcriptase

An enzyme that synthesizes DNA from an RNA template.

Recombinant DNA

DNA that has been formed artificially by combining constituents from different organisms.

Apoptosis

Programmed cell death that removes damaged or dysfunctional cells.

Heterotroph Hypothesis

The idea that the first living organisms were heterotrophs relying on organic molecules for nutrition.

Endosymbiont Hypothesis

The theory that mitochondria and chloroplasts originated as prokaryotic cells engulfed by eukaryotic cells.

Convergent Evolution

The process where unrelated organisms develop similar traits due to adapting to similar environments.

Molecular Clock

A method of estimating the timing of evolutionary events based on DNA mutations.

Genetic Drift

Random fluctuations in the frequency of alleles in a population.

Gene Flow

The transfer of alleles or genes from one population to another.

R Plasmids

Plasmids that carry genes for antibiotic resistance.

F Plasmids

Plasmids that contain genes necessary for the transfer of genetic material during bacterial conjugation.

Prokaryotic

Organisms that lack a nucleus or other membrane-bound organelles, includes bacteria and archaea.

Obligate Anaerobes

Organisms that cannot survive in the presence of oxygen.

Facultative Anaerobes

Organisms that can survive with or without oxygen.

Archaea

A domain of prokaryotic microorganisms that are distinct from bacteria and often live in extreme environments.