Molecular Biology and Cell Division Review

Vocabulary flashcards covering the basics of DNA structure, replication, protein synthesis, the cell cycle, and mitosis as detailed in the lecture notes.

Know the structure of DNA and the importance of complementary base pairing.

 DNA is a double helix made of two strands of nucleotides. Each nucleotide contains a sugar, phosphate, and nitrogen base. The bases pair in a specific way: Adenine (A) pairs with Thymine (T) and Cytosine (C) pairs with Guanine (G). Complementary base pairing allows DNA to copy itself accurately during replication and keeps genetic information the same.

DNA replication

The process of making an exact copy of DNA before cell division, occurring in the nucleus during the S phase of interphase.

Semi-conservative

A characteristic of DNA replication where each new DNA molecule is composed of one original strand and one new strand.

Helicase

An enzyme that unzips the DNA double helix by breaking hydrogen bonds during replication.

Primase

The molecule that adds RNA primers to the DNA strands to initiate replication.

DNA polymerase

An enzyme that adds complementary DNA nucleotides to each individual DNA strand.

DNA ligase

The enzyme responsible for joining DNA fragments together to complete the DNA replication process.

Gene expression

The process of using information in DNA to create a protein, involving transcription and translation.

Transcription

The first step of gene expression where RNA polymerase reads a DNA gene to create a complementary pre-mRNA strand.

mRNA processing

The modification of pre-mRNA by removing introns, joining exons, and adding a $5'$ cap and poly-A tail.

Translation

The process by which a ribosome reads mRNA codons and tRNA molecules bring corresponding amino acids to assemble a protein.

Codon

A sequence of three mRNA bases that codes for a specific amino acid according to a codon chart.

Mutation

Any change in the DNA sequence that can potentially alter the sequence of amino acids and the function of a protein.

Haploid ($n$)

Cells containing only one set of chromosomes, such as sperm and egg cells.

Diploid ($2n$)

Cells containing two sets of chromosomes, one inherited from each parent; most body cells fall into this category.

Chromosome

A tightly coiled package of DNA and proteins that contains genetic information and becomes visible during cell division.

Sister chromatids

Two identical copies of a chromosome joined together at the centromere after DNA replication has occurred.

Homologous chromosomes

Pairs of chromosomes that contain the same genes in the same locations, with one coming from each parent.

Cell cycle

The series of steps a cell undergoes to grow, copy its DNA, and divide into two new cells.

G1 Phase

The first stage of the cell cycle where the cell grows and performs normal functions.

S Phase

The specific stage of interphase where DNA replication occurs.

G2 Phase

The stage where the cell continues to grow and makes final preparations for division.

M Phase

The part of the cell cycle consisting of mitosis (nuclear division) and cytokinesis (cytoplasmic division).

Binary fission

The simplified method of cell division used by prokaryotes which have a single circular chromosome and no nucleus.

Cyclins and CDKs

Regulatory molecules that control the timing and progression of the cell cycle through various stages.

Tumor suppressor genes

Genes that help prevent cancer by slowing cell division, repairing damaged DNA, or inducing cell death in damaged cells.

Mitosis

A process of nuclear division intended to produce two genetically identical diploid daughter cells for growth and repair.

Prophase

The stage of mitosis where chromosomes condense, the nuclear membrane disappears, and spindle fibers begin to form.

Metaphase

The stage of mitosis where chromosomes align along the middle of the cell.

Anaphase

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

Telophase

The final stage of mitosis where new nuclei form around the two sets of chromosomes and the chromosomes begin to uncoil.

Cytokinesis

The final division of the cytoplasm resulting in the creation of two separate, identical daughter cells.