Evolutionary Biology: Chromosomes, Recombination, and DNA

Flashcards covering key vocabulary from the 'Chromosomes and recombination' and 'What does DNA do?' sections of the Evolutionary Biology lecture, including definitions of genetic structures, processes, and central dogma concepts.

Chromosomes

Structures discovered in 1879 and linked to inheritance in 1900-1902; they come in pairs and carry genetic information.

Human Chromosome Count

Humans have a total of 46 chromosomes, with 23 inherited from the mother and 23 from the father.

Karyotypes

Maps showing paired chromosomes, used to visualize an individual's complete set of chromosomes.

Homologous Chromosomes

A pair of chromosomes (one from each parent) that are similar in length, gene position, and centromere location.

Chromatid

One of two identical copies of a replicated chromosome, joined at the centromere.

Sister Chromatids

Two identical chromatids that are connected by a centromere, formed after DNA replication.

Centromere

The specialized region of a chromosome that links sister chromatids and serves as the attachment point for spindle fibers during cell division.

Mitosis

A type of cell division that results in two daughter cells genetically identical to the parent cell, primarily for organismal growth and repair, where sister chromatids separate.

Meiosis

A type of cell division that produces four haploid cells (gametes) from a diploid cell, involving two rounds of division and recombination.

Haploid (1N)

A cell or organism having one complete set of chromosomes.

Diploid (2N)

A cell or organism having two complete sets of chromosomes, one from each parent.

Polyploid (xN)

A cell or organism having more than two complete sets of chromosomes.

Ploidy

Refers to the number of complete sets of chromosomes in a cell.

Sex Chromosomes

A pair of chromosomes that determine an individual's biological sex, often differing from other homologous pairs.

Crossing Over

The exchange of genetic material between non-sister chromatids of homologous chromosomes during meiosis I, leading to new combinations of genes.

Recombination

The process that results from an entire set of crossovers, leading to genetic variation and new combinations of alleles on chromosomes.

Gene Linkage

The phenomenon where genes located close together on the same chromosome tend to be inherited together, which recombination can eliminate.

Gene

A term coined by Wilhelm Johannsen in 1909, later understood to be units of heredity located on chromosomes.

DNA (Deoxyribonucleic Acid)

The molecule that genes are made of, identified by Avery, McCarty, and MacLeod (1944), and whose double helix structure was described by Franklin, Watson, and Crick (1953).

Double Helix

The characteristic spiral-staircase structure of DNA, composed of two polynucleotide strands wound around each other.

Nucleotide

The basic building block of DNA and RNA, consisting of a sugar, a phosphate group, and one of four nitrogenous bases (adenine, guanine, cytosine, thymine/uracil).

DNA Replication

The biological process of producing two identical replicas of DNA from one original DNA molecule, which occurs semi-conservatively.

Semiconservative Replication

The mechanism of DNA replication in which each new DNA molecule consists of one original parental strand and one newly synthesized daughter strand.

DNA Polymerase

The enzyme crucial for DNA replication, responsible for matching existing nucleotides with new bases to synthesize a new DNA strand.

Central Dogma

The fundamental concept in molecular biology that describes the flow of genetic information in a cell from DNA to RNA to protein.

Transcription

The first step of the central dogma, where genetic information from a DNA segment is copied into an RNA molecule (occurs in the nucleus).

Translation

The second step of the central dogma, where the genetic code in mRNA is read by ribosomes to produce a specific protein (occurs in the cytosol).

RNA (Ribonucleic Acid)

A single-stranded nucleic acid that contains uracil instead of thymine, playing various roles in gene expression and protein synthesis.

Protein

Complex macromolecules formed from chains of amino acids, performing a wide array of functions essential for cell structure, function, and regulation.

Amino Acid

The building blocks of proteins, with 20 different types, each characterized by a unique R group, an amino group, and a carboxyl group.

Codon

A sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule, specifying a particular amino acid or stop signal during protein synthesis.

Universality of the Genetic Code

The principle that the same codons specify the same amino acids in almost all organisms, serving as strong evidence for a common evolutionary heritage.

Cytochrome C

A small, highly conserved protein involved in the electron transport chain, often used for comparing genetic relatedness between species based on its amino acid sequence.