Biology 30: Cell Division

These flashcards cover key vocabulary and concepts related to cell division, genetics, and the life cycles of organisms in preparation for the exam.

Chromosomes

Structures composed of genes that carry genetic information.

The person who made the discovery of chromosomes and mitosis

Walter Flemming in 1882.

Mitosis

A term from Greek meaning 'thread,' referring to the thread-like appearance of chromosomes during division. A fundamental process of eukaryotic cell division that replicates a cell's chromosomes and distributes them evenly to produce two genetically identical daughter cells.

Significance of mitosis

Crucial for tissue repair and growth.

Gametogenesis

The process of forming gametes for sexual reproduction.

Chemical structure of chromosomes

Chromosomes are composed of chromatin, which is 50% nucleic acid and 50% proteins.

Types of proteins in chromosomes

Acidic (non-histone) proteins called phosphoproteins and basic proteins (histones).

Role of histones in chromosomes

Protect the DNA molecule and aid in the super-coiling process.

Chromosome count in humans

Humans have 23 pairs, totaling 46 chromosomes.

Ploidy

The number of homologous chromosomes an organism has.

Common ploidy level in organisms

Diploid (2n), meaning having pairs of chromosomes.

Tetraploid organism

An organism with four sets of chromosomes (4n).

Homologous chromosomes

Similar in shape and length, carrying the same types of characteristics.

Sister chromatids

Identical copies of a chromosome that may be attached at the centromere before division.

Function of telomeres

Protect the ends of chromosomes and are vital for chromosome survival.

Structure of a chromosome

Consists of a short (p) arm, a long (q) arm, a centromere, and telomeres.

Triploid organism

Has three sets of chromosomes (3n) and may be sterile.

Role of genes in chromosomes

Unique segments that represent specific traits and control biological processes.

Significance of genetic information

Determines the structure and function of organisms and how they interact with their environment.

Types of chromosomes in somatic cells

Maternal chromosomes (from the mother) and paternal chromosomes (from the father).

Chromosome number and organism complexity

The number of chromosomes does not determine the complexity of an organism.

Simplest form of cell division in prokaryotes

Binary fission.

Main functions of chromosomes

Transcription/translation, replication, and recombination.

Transcription

Ribonucleic acid (RNA) is built from DNA.

Primary function of DNA

Transcription and translation of genetic material.

Replication in chromosomes

Chromosomes make copies of themselves before cellular division.

Recombination in chromosomes

Process during cellular division where chromosomes swap genetic information, increasing genetic variability.

Interphase in the cell cycle

Phase where cells grow and prepare for division, spending most time in this phase.

Phases of interphase

G1 (gap), S (synthesis), and G2 (gap).

G1 phase of interphase

Cells grow after mitosis and prepare for DNA replication.

S phase of interphase

Chromosomal DNA is replicated.

G2 phase of interphase

Cells grow and produce proteins for two new cells.

Mitosis

Process by which eukaryotic cells divide.

Phases of karyokinesis

Prophase, metaphase, anaphase, and telophase.

Prophase

Replicated chromosomes condense, nuclear membrane breaks down, and spindle fibers form.

Metaphase

Chromosomes line up at the metaphase plate and attach to spindle fibers.

Anaphase

Chromatids separate and move to opposite poles of the cell.

Telophase

Chromosomes decondense, nuclear membranes form, and spindle fibers disintegrate.

Cytokinesis

Division of the cytoplasm to form two new daughter cells.

Cytokinesis in plant vs animal cells

In plants, a cell plate forms; in animals, the membrane pinches in at the cleavage furrow.

Karyotype

Analytical tool used to identify chromosomal abnormalities in cells.

Trisomy 21

Also known as Down syndrome.

Effects of Trisomy 21

Mental retardation, webbed fingers and toes, slanted eyes, and short stature.

Klinefelter syndrome

Condition in males with an extra X chromosome (XXY), leading to sterile males with female hormone characteristics.

Turner syndrome

Condition in females characterized by a missing X chromosome (XO), leading to short stature and other effects.

Significance of karyotype in prenatal testing

Used to check for chromosomal disorders in fetuses.

Karyotype sample preparation

Cell sample taken from amniocentesis or chorionic villi sampling.

Karyotype abnormalities

Look for extra chromosomes or chromosomes with added or deleted sections.

Mitotic natural cloning

A form of asexual reproduction where identical offspring are formed from a single cell or tissue.

Clone

Identical offspring formed from a single cell or tissue.

Binary fission

Type of asexual reproduction where prokaryotic or eukaryotic cells equally divide their cytoplasm and nucleus.

Budding

Form of asexual reproduction where the nucleus divides equally but the cytoplasm divides unequally, forming new cells that may live independently or as colonies.

Sporulation

Production of spores, specialized cells released from the parent and developed under favorable conditions.

Fragmentation in asexual reproduction

Development of a new organism from a part of an original organism, like a starfish regenerating from an arm.

Vegetative propagation

A form of asexual reproduction in plants involving bulbs, tubers, runners, and rhizomes.

Dolly the sheep

First mammal cloned from an adult somatic cell using nuclear transfer.

Technique to create Dolly

Somatic cell nuclear transfer, transferring nucleus from an adult cell into an unfertilized egg cell.

Significance of telomeres

Protect the ends of chromosomes from deterioration and prevent fusion with neighboring chromosomes.

Telomere shortening during cell division

Telomeres shorten with each division, eventually leading to cellular senescence.

Cancer characteristics

Rapid, uncontrolled cell growth and ability to reproduce in isolation, often forming tumors.

Role of telomerase in cells

Replenishes telomeres, allowing cells to continue dividing beyond their normal limit.

Maximum life span of human cells

Approximately 115 years, with most cells having a finite number of divisions.

Common cancer treatments

Focus on eliminating carcinogenic substances, slowing down mitosis, and targeting the immune system against cancer cells.

Specialization and reproductive ability relationship

Reproductive ability decreases as specialization increases.

Embryo splitting

Form of asexual reproduction that can lead to the formation of identical twins.

Surrogate mother role in cloning

Carries the cloned embryo to term after implantation.

Impact of cancer cells

Grow more rapidly than normal cells and do not adhere to other cancer cells, allowing metastasis.

Primary purpose of meiosis

Generate gametes for sexual reproduction and reduce the number of chromosomes by half.

Fusion of two gametes

Syngamy.

Main stages of meiosis

Interphase I, Meiosis I (reduction division), and Meiosis II.

Prophase I of meiosis

Homologous chromosomes pair up and exchange genetic information through crossing-over.

Tetrad in meiosis

A pair of homologous chromosomes attached together during Prophase I.

Metaphase I of meiosis

Homologous chromosomes align along the equatorial plate and attach to spindle fibers.

Segregation in meiosis

Separation of homologous chromosome pairs during Anaphase I.

Outcome of Telophase I

Two secondary gametocytes, each with one homologous pair of sister chromatids.

Interphase II

Resting phase with no DNA replication and incomplete decondensation of chromosomes.

Outcome of Telophase II

Four haploid cells called monads are formed, each varying in structure.

Male vs female gametogenesis

Male is symmetrical, producing four sperm cells; female is asymmetrical, producing one large egg and three polar bodies.

Nondisjunction in meiosis

Homologous chromosomes move to the same pole, resulting in one daughter cell missing a chromosome (monosomy) and another with an extra chromosome (trisomy).

Down syndrome cause

Trisomy of chromosome 21.

Turner's syndrome cause

Monosomy of the X chromosome.

Alternation of generations

Cycling between diploid (2N) and haploid (N) stages in the life cycle of sexually reproducing organisms.

Sporophyte

A diploid (2N) spore-producing body that produces haploid spores through meiosis.

Gametophytes

Haploid (n) bodies that develop from spores and produce gametes.

Advantage of sexual reproduction

Offers genetic variation providing a selective advantage in changing environments.

Parthenogenesis

A form of asexual reproduction where an egg develops into a mature adult without fertilization.

Significance of crossing-over

Increases genetic diversity by allowing the exchange of genetic material between homologous chromosomes.

Anaphase II of meiosis

Sister chromatids are separated and migrate to opposite spindle poles.

Role of telomerase in cancer cells

Allows malignant cells to become immortalized by extending telomeres.