Ch. 3: The Chromosomal Basis of Heredity: Exam #2

These flashcards cover key concepts related to the chromosomal basis of heredity, including details on chromosomes, cell division processes, genetic variation, and other relevant terms.

Chromosomes

Structures that contain genetic material, with different numbers in each species.

Diploid

An organism with two copies of each chromosome, typical in somatic cells.

Haploid

A cell that contains one set of chromosomes, as seen in gametes.

Fertilization

The union of haploid gametes to form a diploid organism.

Mitosis

A type of cell division that produces two genetically identical daughter cells.

Cytokinesis

The process following mitosis where the cell divides to form two daughter cells.

Interphase

The stage of the cell cycle when the cell is not undergoing mitosis.

S Phase

The part of interphase during which DNA is replicated.

G1 Phase

The phase of interphase before DNA synthesis begins.

G2 Phase

The phase of interphase after DNA synthesis where the cell prepares for mitosis.

M checkpoint

A phase in cell cycle where the alignment of chromosomes is checked before proceeding with mitosis.

Prophase

The first stage of mitosis where chromatin condenses into chromosomes.

Metaphase

The stage of mitosis where chromosomes align at the metaphase plate.

Anaphase

The phase in mitosis where sister chromatids are pulled apart to opposite poles.

Telophase

The final stage of mitosis where nuclear membranes form and chromosomes decondense.

Meiosis

A type of cell division resulting in four genetically diverse haploid cells.

Meiocytes

Specialized cells in which meiosis occurs to produce gametes.

Crossing Over

The exchange of genetic material between homologous chromosomes during prophase I of meiosis.

Homologous Chromosomes

Chromosome pairs, one from each parent, that are similar in shape and size.

Reductional Division

The first division in meiosis, where homologous chromosomes are separated.

Equational Division

The second division in meiosis, similar to mitosis, where sister chromatids are separated.

Nucleosome

The basic unit of chromatin, composed of DNA wrapped around histone proteins.

Histones

Proteins that help package and order DNA into structural units called nucleosomes.

Chromatin Fiber

The coiled structure of DNA and proteins that makes up chromosomes.

Euchromatin

Less condensed form of chromatin that is generally transcriptionally active.

Heterochromatin

Tightly condensed form of chromatin that is generally transcriptionally inactive.

Centromere

The region of a chromosome where sister chromatids are joined and spindles attach.

Telomere

The protective cap at the end of a chromosome that prevents degradation.

Telomerase

An enzyme that adds nucleotide sequences to telomeres, maintaining chromosome length.

Senescence

The process where a cell loses the ability to divide, often due to shortened telomeres.

Cohesins

Protein complexes that hold sister chromatids together until anaphase.

Kinetochore

A protein structure on the centromere that attaches spindle fibers to chromosomes.

Spindle Fibers

Protein structures that separate chromosomes during cell division.

Motor Proteins

Proteins that move along the spindle fibers to facilitate chromosomal movement.

Chromatid

Each of the two identical halves of a duplicated chromosome.

Nuclear Envelope

The double membrane that encloses the nucleus.

Cleavage Furrow

The indentation that begins the process of cytokinesis in animal cells.

Oocyte

A female gamete that develops into an egg cell.

Spermatocyte

A male gamete that develops into sperm cells.

Chiasmata

The point where two homologous non-sister chromatids exchange genetic material during crossing over.

Telomere Shortening

The progressive loss of telomere length which can lead to cell senescence.

Histone Acetylation

A modification that typically enhances gene expression by making DNA more accessible.

Histone Methylation

A modification that generally represses gene expression by making DNA less accessible.

Chromatin Condensation

The process where chromatin coils and supercoils into a fully condensed chromosome.

Cytoplasm

The gel-like substance within the cell membrane where organelles are located.

Genetic Diversity

The variation in the DNA sequences among individuals.

Gene

A segment of DNA that contains the information for producing a gene product.

Alleles

Different versions of a gene that can result in varying traits.

Genotype

The genetic constitution of an organism.

Phenotype

The observable characteristics of an organism determined by genotype.

Independent Assortment

The principle that alleles for different traits are distributed to gametes independently.

Genetic Linkage

The tendency of genes located close to each other on a chromosome to be inherited together.

Mutation

A change in the DNA sequence that may lead to alterations in phenotype.

Selection Pressure

Environmental factors that influence which individuals in a population survive and reproduce.

Natural Selection

The process through which advantageous traits increase in frequency within a population.

Speciation

The process by which new biological species arise.

Vertical Gene Transfer

The transmission of genetic material from parent to offspring.

Horizontal Gene Transfer

The transfer of genetic material between organisms other than through reproduction.

Biodiversity

The variety of life in the world or in a particular habitat or ecosystem.

Polygenic Trait

A trait controlled by two or more genes.

Epigenetics

The study of changes in gene expression caused by mechanisms other than changes in the DNA sequence.

Genome

The complete set of genes or genetic material present in a cell or organism.

Transcription

The process of copying a segment of DNA into RNA.

Translation

The process by which ribosomes synthesize proteins based on mRNA sequences.

Intron

A non-coding segment of DNA that is removed during RNA processing.

Exon

A coding segment of DNA that is retained in RNA after processing.

RNA Splicing

The process of removing introns and joining exons to form a mature mRNA strand.

Recombinant DNA

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

Gene Therapy

The therapeutic technique that uses genes to treat or prevent disease.

Stem Cell

Undifferentiated cells with the potential to develop into various cell types.

Apoptosis

Programmed cell death that is a normal component of development and health.

Cell Differentiation

The process by which generalized cells develop into specialized cells.

Genomic Imprinting

A genetic phenomenon where certain genes are expressed in a parent-of-origin-specific manner.

Carcinogenesis

The process by which normal cells are transformed into cancer cells.

Oncogene

A mutated gene that has the potential to cause cancer.

Tumor Suppressor Gene

A gene that regulates cell division, preventing uncontrolled cell growth.

Apoptosome

A large protein complex formed in the process of apoptosis.

Cell Cycle Arrest

A halt in the cell cycle to allow for repair or to prevent damaged cells from dividing.