Cellular Reproduction, Genetics, and Molecular Biology Review

Sister chromatids

Identical copies of a chromosome connected by a centromere, formed during DNA replication.

Centromere

The region of a chromosome where sister chromatids are joined and where the spindle fibers attach during cell division.

Cell cycle

The series of events that take place in a cell leading to its division and replication, consisting of interphase and the mitotic phase.

Interphase

The phase of the cell cycle where the cell grows, duplicates its DNA, and prepares for mitosis.

Mitosis

The process of cell division that results in two genetically identical daughter cells from a single parent cell.

Prophase

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

Metaphase

The stage of mitosis where chromosomes align at the cell's equatorial plane and spindle fibers attach to the centromeres.

Anaphase

The phase of mitosis where sister chromatids are pulled apart to opposite poles of the cell.

Telophase

The final stage of mitosis where chromosomes de-condense, nuclear envelopes reform, and the cell prepares to divide.

Mitotic spindle

A structure made of microtubules that segregates chromosomes during cell division.

Cleavage furrow

The indentation that begins the process of cytokinesis in animal cells, leading to cell division.

Cell plate

The structure that forms during cytokinesis in plant cells, leading to the separation of the two daughter cells.

Cell cycle checkpoints

Regulatory points in the cell cycle that ensure proper division and prevent errors such as DNA damage or incomplete replication.

Cancer

A disease characterized by uncontrolled cell growth and division, often due to mutations in genes that regulate the cell cycle.

Homologous chromosomes

Pairs of chromosomes that have the same structure and gene sequence, one inherited from each parent.

Diploid

A cell or organism that has two complete sets of chromosomes, one from each parent (2n).

Haploid

A cell or organism that has one complete set of chromosomes (n), such as gametes.

Gametes

Reproductive cells (sperm and eggs) that are haploid and combine during fertilization.

Fertilization

The process by which a sperm cell and an egg cell combine to form a zygote.

Meiosis

The type of cell division that reduces the chromosome number by half, producing four haploid gametes.

Karyotype

A visual representation of an individual's chromosomes, used to assess genetic disorders.

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate properly during cell division, leading to an abnormal number of chromosomes.

Genetics

The study of heredity and the variation of inherited characteristics.

True-breeding

Organisms that, when mated, produce offspring with the same traits as the parents.

Hybrid

The offspring resulting from the cross of two different true-breeding varieties.

P generation

The parental generation in a genetic cross.

F1 Generation

The first generation of offspring from a genetic cross.

F2 Generation

The second generation of offspring, produced by interbreeding the F1 generation.

Alleles

Different versions of a gene that determine specific traits.

Homozygous

An organism that has two identical alleles for a particular gene.

Heterozygous

An organism that has two different alleles for a particular gene.

Dominant

An allele that expresses its trait even in the presence of a recessive allele.

Recessive

An allele that expresses its trait only when two copies are present.

Genotype

The genetic makeup of an organism, represented by its alleles.

Phenotype

The observable characteristics or traits of an organism, determined by its genotype.

Monohybrid cross

A genetic cross that examines the inheritance of a single trait.

Dihybrid cross

A genetic cross that examines the inheritance of two traits simultaneously.

Incomplete dominance

A genetic scenario where the phenotype of heterozygotes is intermediate between the phenotypes of the homozygotes.

Codominant

A genetic scenario where both alleles in a heterozygote are fully expressed.

Multiple alleles

A situation in which three or more alleles exist for a particular gene.

Sex-linked genes

Genes located on the sex chromosomes, often leading to traits that are expressed differently in males and females.

Sex chromosomes

Chromosomes that determine the sex of an organism, typically X and Y in humans.

X-linked genes

Genes located on the X chromosome, often affecting males more severely due to the presence of only one X chromosome.

Nucleotide

The basic building block of nucleic acids, consisting of a sugar, a phosphate group, and a nitrogenous base.

Deoxyribonucleic acid (DNA)

The molecule that carries genetic information in living organisms, composed of two strands forming a double helix.

Sugar-phosphate backbone

The structural framework of nucleic acids, consisting of alternating sugar and phosphate groups.

Helicase

An enzyme that unwinds the DNA double helix during replication.

Double helix

The twisted ladder structure of DNA formed by two strands of nucleotides.

Semiconservative model

The model of DNA replication where each new DNA molecule consists of one original strand and one new strand.

DNA polymerase

An enzyme that synthesizes new DNA strands by adding nucleotides to a growing chain during replication.

DNA ligase

An enzyme that joins Okazaki fragments together during DNA replication.

Okazaki fragment

Short segments of DNA synthesized on the lagging strand during DNA replication.

Transcription

The process of synthesizing RNA from a DNA template.

Translation

The process of synthesizing proteins from an mRNA template.

Codon

A sequence of three nucleotides in mRNA that specifies a particular amino acid.

RNA polymerase

An enzyme that synthesizes RNA by following a strand of DNA.

Messenger RNA (mRNA)

The type of RNA that carries genetic information from DNA to the ribosome for protein synthesis.

Introns

Non-coding sequences in a gene that are removed during RNA processing.

Exons

Coding sequences in a gene that are expressed and retained during RNA processing.

RNA processing

The modification of RNA after transcription, including splicing and the addition of a 5' cap and poly-A tail.

Transfer RNA (tRNA)

The type of RNA that carries amino acids to the ribosome during protein synthesis.

Anticodon

A sequence of three nucleotides in tRNA that pairs with a complementary codon in mRNA.

Ribosomal RNA (rRNA)

The type of RNA that makes up the major part of ribosomes and is essential for protein synthesis.

Mutation

A change in the DNA sequence that can lead to alterations in gene function and may result in genetic disorders.