DNA, Genetics, Cell Division, and Karyotypes

Comprehensive vocabulary flashcards covering DNA structure, cell division, mitosis, meiosis, genetic variation, karyotyping, genetic disorders, and prenatal testing.

Heredity

The process of passing traits from parents to offspring.

Genetics

The scientific study of heredity and variation.

Genetic material

All the material in an organism that stores genetic information.

DNA (deoxyribonucleic acid)

The molecule that contains genetic information.

Gene

A section of DNA that contains information that helps produce a particular trait.

Locus

The specific location of a gene on a chromosome.

Diploid cells

Cells with two sets of chromosomes ($2n$).

Haploid cells

Cells with half the normal number of chromosomes ($n$).

Polyploid cells

Cells containing three or more sets of chromosomes.

Asexual reproduction

A form of reproduction that uses one parent and produces offspring that are generally genetically identical to the parent.

Sexual reproduction

A form of reproduction involving the fusion of two sex cells (gametes), producing genetically different offspring.

Friedrich Miescher

Scientist who discovered a substance in cells that he called nuclein, which was later recognized as DNA.

Joachim Hammerling

Scientist whose experiments with algae showed that the nucleus contains genetic information controlling the organism.

Hershey & Chase

Scientists whose experiments with bacteriophages showed that DNA is the genetic material.

Phoebus Levene

Scientist who discovered the three components of DNA: sugar, phosphate group, and nitrogenous base.

Nucleotide

The basic building block of DNA consisting of three components: a sugar, a phosphate group, and a nitrogenous base.

Erwin Chargaff

Scientist who discovered that $A = T$ and $C = G$ in DNA.

Complementary base pairing

The rule governing DNA bases where adenine pairs with thymine ($A \leftrightarrow T$) and cytosine pairs with guanine ($C \leftrightarrow G$).

Cell cycle

The series of events a cell goes through as it grows and divides.

$G_1$ phase

The growth stage of interphase where the cell grows, makes proteins, produces ATP, and duplicates organelles.

$S$ phase

The synthesis stage of interphase during which DNA is replicated.

$G_2$ phase

The preparation stage of interphase where the cell prepares for division, checks copied DNA, and performs final metabolic reactions.

$$G_0$$

A resting/quiescent state where a cell stops dividing.

Amitotic

A term describing a cell that does not undergo cell division.

Prophase

The first stage of mitosis where DNA supercoils/condenses into visible chromosomes, spindle fibres begin forming, and the nuclear membrane breaks down.

Metaphase

The stage of mitosis where chromosomes line up in the middle/equator of the cell and spindle fibres attach to them.

Anaphase

The stage of mitosis where sister chromatids separate and move toward opposite poles of the cell.

Telophase

The final stage of mitosis where chromosomes reach opposite poles, new nuclear membranes form, and chromosomes uncoil.

Cytokinesis

The division of the cytoplasm that occurs to produce daughter cells.

Tumour

A mass of cells caused by uncontrolled cell division.

Tumour suppressor genes

Genes that produce proteins that stop or inhibit cell division.

Proto-oncogenes

Genes that produce proteins that promote growth and cell division.

Meiosis

A type of cell division that produces sex cells (gametes), yielding 4 genetically different haploid cells from 1 diploid cell.

Sister chromatids

Two genetically identical copies of a chromosome made during $S$ phase, joined at a centromere and separated during mitosis or meiosis II.

Crossing over

The exchange of DNA between non-sister chromatids of homologous chromosomes occurring during Prophase I.

Chiasmata

The exchange points where crossing over takes place between homologous chromosomes.

Random assortment

The random lining up of homologous chromosome pairs during Metaphase I, generating $2^n$ possible combinations in gametes.

Spermatogenesis

The process that produces 4 haploid sperm cells in the seminiferous tubules of the testes.

Oogenesis

The process that produces 1 functional haploid egg cell and polar bodies in the ovaries.

Karyotype

A picture of an organism's chromosomes arranged into homologous pairs from largest to smallest, ending with sex chromosomes.

Homologous chromosomes

Matching pairs of chromosomes that are about the same height/size, have the same banding pattern, and have their centromere in the same location.

Nondisjunction

An error when chromosomes do not separate properly during cell division.

Monosomy

A condition in which a person has one chromosome missing from a pair.

Trisomy

A condition in which a person has three copies of a chromosome instead of two.

Down syndrome

A genetic disorder caused by an extra copy of chromosome 21 (trisomy 21), characterized by developmental delays, characteristic facial features, and possible heart problems.

Klinefelter syndrome

A genetic condition where a male has an extra X chromosome (XXY), often causing taller than average height, reduced testosterone, and possible fertility difficulties.

Turner syndrome

A genetic condition where a female is missing all or part of one X chromosome (usually XO), leading to shorter height, underdeveloped ovaries, and possible fertility difficulties.

Chorionic Villus Sampling (CVS)

A prenatal test in which a small sample of tissue from the placenta is taken to test for genetic disorders.

Maternal Multiple Marker Screening (MMS)

A screening blood test from the mother measuring substances in her blood to estimate the chance of certain birth defects or chromosome conditions.

Amniocentesis

A prenatal test in which a small sample of fluid around the baby is taken and tested for chromosome or genetic problems.