Chapter 04 Lecture: DNA Structure, Function, and Cell Cycle

Flashcards covering DNA structure, function, nucleotide components, base pairing, genes, genomes, RNA characteristics, and the phases of the cell cycle and mitosis.

Deoxyribonucleic acid (DNA)

A long, thread-like molecule with uniform diameter but varied length, composed of 46 molecules (chromosomes) in the nucleus of most human cells.

Nucleotide

The polymer subunit of DNA and other nucleic acids, consisting of a sugar, phosphate group, and nitrogenous base.

Deoxyribose

The sugar component found in a DNA nucleotide.

Purines

Nitrogenous bases with a double-ring structure, including Adenine (A) and Guanine (G).

Pyrimidines

Nitrogenous bases with a single-ring structure, including Cytosine (C) and Thymine (T) in DNA, and Uracil (U) in RNA.

DNA bases

The four nitrogenous bases found in DNA: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).

Double helix

The spiral staircase-like shape of DNA, where each sidepiece is a backbone of alternating phosphate groups and deoxyribose.

Hydrogen bonds (in DNA)

Bonds that unite nitrogenous bases between the two strands of the DNA double helix (A-T with two bonds, C-G with three bonds).

Law of complementary base pairing

The principle that in DNA, one strand's base sequence determines the base sequence of the other strand (A pairs with T, C pairs with G).

Gene

A segment of DNA that codes for the synthesis of a specific protein.

Genome

All the genes of one person, including approximately 20,000 genes in humans, which make up about 2% of total DNA.

Noncoding DNA

The approximately 98% of total DNA that does not code for proteins but plays a role in chromosome structure and regulation of gene activity.

Ribonucleic acids (RNAs)

Smaller molecules that resemble DNA but have a single nucleotide chain, contain ribose instead of deoxyribose, and uracil replaces thymine; they function mainly in the cytoplasm.

Messenger RNA (mRNA)

One of the three important types of RNA involved in protein synthesis.

Ribosomal RNA (rRNA)

One of the three important types of RNA involved in protein synthesis.

Transfer RNA (tRNA)

One of the three important types of RNA involved in protein synthesis.

Ribose

The sugar component that replaces deoxyribose in RNA.

Uracil (U)

The nitrogenous base that replaces thymine in RNA.

G1 phase (First Gap Phase)

The interval between cell birth and DNA replication, during which the cell carries out normal tasks and accumulates materials for the next phase.

S phase (Synthesis Phase)

The phase during which a cell replicates all nuclear DNA and duplicates centrioles.

G2 phase (Second Gap Phase)

The interval between DNA replication and cell division, where the cell repairs DNA replication errors, grows, and synthesizes enzymes for cell division.

M phase (Mitotic Phase)

The phase during which a cell replicates its nucleus and pinches in two to form new daughter cells.

Mitosis

Cell division that results in two genetically identical daughter cells, functioning in development, tissue growth, cell replacement, and tissue repair.

Prophase

The first phase of mitosis, characterized by chromosome condensation.

Metaphase

The second phase of mitosis, where chromosomes align at the metaphase plate.

Anaphase

The third phase of mitosis, during which sister chromatids separate and move to opposite poles.

Telophase

The fourth and final phase of mitosis, where nuclear envelopes reform around the separated chromosomes.