Grade 11 Biology: Genetics, Mitosis, Meiosis, and Reproduction Study Guide

Vocabulary practice flashcards covering Genetics, Mitosis, Meiosis, Gametogenesis, Chromosomal Disorders, Prenatal Testing, and Reproductive Technologies based on Grade 11 Biology lecture notes.

Genetics

The study of heredity: how characteristics are passed from parents to offspring.

DNA (Deoxyribonucleic Acid)

The molecule that stores genetic information, structured as a double helix composed of repeating nucleotide units.

Gene

A segment of DNA that codes for a particular trait or product.

Chromosome

A long DNA molecule packaged with proteins that carries many genes.

Trait

An inherited characteristic, such as a feature of appearance.

Allele

A different version of the same gene.

Locus

The specific physical location of a gene on a chromosome (plural: loci).

Nucleotide

A repeating structural unit of DNA consisting of three parts: a deoxyribose sugar, a phosphate group, and a nitrogenous base.

Semiconservative Replication

The mechanism of DNA replication in which each newly formed DNA molecule contains one original template strand and one newly synthesized strand.

Histone

A structural protein that DNA wraps around during the initial stage of chromosome packaging.

Nucleosome

A structural unit of chromatin consisting of a section of DNA coiled around histone proteins.

Chromatin

DNA combined with structural proteins in a less condensed, uncoiled form present during interphase.

Chromatid

One of the two identical copies of a duplicated chromosome.

Centromere

The constricted region of a chromosome that holds sister chromatids together and serves as an attachment site for spindle fibres.

Homologous Chromosomes

A pair of matching chromosomes (one maternal, one paternal) similar in length, centromere location, and banding pattern that carry genes for the same traits at the same loci.

Sister Chromatids

Two identical copies of a single replicated chromosome attached together at the centromere.

Autosomes

Chromosomes 1 through 22 in humans that code for most inherited traits and do not determine biological sex.

Sex Chromosomes

The 23rd chromosome pair in humans (typically XX or XY) that determines genetic sex.

Karyotype

A photographic arrangement of an individual's chromosomes sorted into homologous pairs during metaphase to evaluate chromosome number and structure.

Cell Cycle

The three continuous stages a cell passes through as it grows and divides: interphase, mitosis, and cytokinesis.

Interphase

The longest and highly active stage of the cell cycle during which the cell grows, carries out normal metabolic functions, copies its DNA, and replicates organelles.

Mitosis

The division of the cell nucleus that separates duplicated chromosomes to produce two genetically identical diploid ($2n$) nuclei.

Cytokinesis

The division of the cytoplasm and organelles to separate a dividing cell into two distinct daughter cells.

Prophase (Mitosis)

The first phase of mitosis where chromatin condenses into visible double-stranded chromosomes, the nuclear membrane breaks down, and spindle fibres form.

Metaphase (Mitosis)

The second phase of mitosis during which chromosomes line up individually along the equator or metaphase plate of the cell.

Anaphase (Mitosis)

The phase of mitosis where centromeres split and sister chromatids separate into daughter chromosomes, pulled to opposite poles by spindle fibres.

Telophase (Mitosis)

The final phase of mitosis where daughter chromosomes reach opposite poles, uncoil, and new nuclear membranes form around each set of genetic material.

Cleavage Furrow

A shallow groove formed by the pinching inward of the cell membrane at the equator during animal cell cytokinesis.

Cell Plate

A structure that forms along the equator of a dividing plant cell during cytokinesis and eventually develops into a new rigid cell wall.

Spindle Fibres

Specialized protein structures that attach to chromosomes at the centromere to position them at the cell equator and separate them during division.

Cell-Cycle Checkpoints

Internal and external control points that monitor cell conditions (signals, nutrients, DNA replication, and DNA damage) before permitting division to continue.

Meiosis

A two-stage cell division process in gonads that reduces the chromosome number by half ($2n \rightarrow n$), producing four genetically diverse haploid gametes.

Gamete

A specialized haploid ($n$) reproductive sex cell, namely a sperm or an ovum.

Gonads

The primary reproductive organs that produce gametes: testes in males and ovaries in females.

Fertilization

The fusion of a haploid sperm and a haploid egg to restore the diploid ($2n$) chromosome number, producing a zygote.

Zygote

A single diploid ($2n$) cell produced by the union of two haploid gametes during fertilization.

Synapsis

The physical pairing of homologous chromosomes during Prophase I of meiosis.

Tetrad

A four-chromatid structure formed during Prophase I consisting of two paired homologous chromosomes.

Crossing Over

The exchange of genetic material between non-sister chromatids of homologous chromosomes at chiasmata during Prophase I.

Chiasma

The physical site or crossover point where non-sister chromatids exchange segments during crossing over (plural: chiasmata).

Independent Assortment

The random orientation and alignment of maternal and paternal homologous chromosome pairs along the metaphase plate during Metaphase I.

Meiosis I

The reduction division of meiosis that separates homologous chromosome pairs, reducing the chromosome count from diploid ($2n$) to haploid ($n$).

Meiosis II

The second division of meiosis that separates sister chromatids without an intervening round of DNA replication, maintaining the haploid ($n$) state.

Spermatogenesis

The continuous process in mammalian testes, beginning at puberty, that produces four functional haploid sperm from one primary spermatocyte.

Sperm Midsection

The middle segment of a mature sperm cell packed with mitochondria to produce ATP energy for flagellar locomotion.

Oogenesis

The process in the ovaries that begins before birth and produces one large, functional haploid ovum and smaller non-functional polar bodies per cycle.

Polar Body

A small, non-viable cell produced during unequal meiotic divisions in oogenesis that receives minimal cytoplasm and eventually degenerates.

Follicular Fluid

Fluid surrounding the developing egg within an ovarian follicle that releases chemical and hormonal cues to guide and select sperm.

Deletion

A structural chromosomal alteration in which a piece of a chromosome breaks off and is permanently lost.

Duplication

A structural chromosomal alteration where a specific segment appears two or more times in a row along a chromosome.

Inversion

A structural chromosomal alteration in which a segment breaks off, reverses its physical orientation, and reattaches to the same chromosome.

Translocation

A structural chromosomal alteration occurring when a piece of one chromosome breaks off and attaches to a non-homologous chromosome.

Cri-du-Chat Syndrome

A genetic condition caused by a deletion in chromosome 5, associated with developmental delays and a distinctive high-pitched, cat-like infant cry.

Chronic Myelogenous Leukemia (CML)

A white blood cell cancer caused by a reciprocal translocation between chromosomes 9 and 22 that produces the abnormal Philadelphia chromosome.

Nondisjunction

The failure of homologous chromosomes (during Anaphase I) or sister chromatids (during Anaphase II) to separate properly, creating abnormal gametes.

Trisomy

A chromosomal condition in which an individual has three copies of a specific chromosome instead of the normal two ($2n + 1$).

Monosomy

A chromosomal condition in which an individual has only one copy of a specific chromosome instead of the normal two ($2n - 1$).

Down Syndrome

A genetic disorder resulting from Trisomy 21 (an extra chromosome 21), characterized by intellectual challenges, flattened facial features, and short stature.

Turner Syndrome

A genetic condition resulting from monosomy X ($45,X$) where a female possesses only one X chromosome, causing short stature and underdeveloped reproductive organs.

Prenatal Genetic Testing

Medical testing performed during pregnancy to assess a developing fetus for potential genetic, structural, or chromosomal disorders.

Screening Test

A non-invasive prenatal test (such as ultrasound or maternal blood sampling) that provides a risk estimate rather than a definitive diagnosis of fetal conditions.

Diagnostic Test

An invasive prenatal medical procedure (such as amniocentesis or CVS) that directly analyzes fetal genetic material to definitively identify or rule out abnormalities.

Amniocentesis

An invasive prenatal diagnostic procedure where a needle extracts amniotic fluid containing shedding fetal cells for chromosomal analysis.

Chorionic Villus Sampling (CVS)

An invasive prenatal diagnostic procedure where a small tissue sample of chorionic villi is retrieved from the placenta to assess fetal genetics.

Artificial Insemination

A reproductive technology in which collected and concentrated sperm is manually introduced directly into the female reproductive tract.

In Vitro Fertilization (IVF)

A fertility treatment where eggs are retrieved and fertilized with sperm outside the body in a petri dish before healthy embryos are transferred to the uterus.

Preimplantation Genetic Diagnosis (PGD)

A molecular screening procedure performed on IVF embryos before implantation to identify specific chromosomal or genetic disorders.

Gene Cloning

The process of inserting a foreign gene into a bacterial plasmid to create recombinant DNA, which is transformed into bacteria to mass-produce genes or proteins.

Therapeutic Cloning

The use of somatic cell nuclear transfer (SCNT) to generate patient-matched embryonic stem cells capable of forming tissues or organs for medical treatments.

Reproductive Cloning

The use of somatic cell nuclear transfer (SCNT) into an enucleated egg followed by surrogate mother implantation to produce a live, genetically identical organism.

Transgenic Organism

A genetically modified organism (GMO) whose genome contains functional DNA transferred from a completely different species.