BA Ch 3

Flashcards about Genetics and Genomes

Prokaryotes

Single-celled organisms without nuclear membranes or organelles; genetic material is a single strand in the cytoplasm.

Eukaryotes

Multi-celled organisms with a membrane-bound nucleus containing genetic material and specialized organelles.

Cytoplasm

The area surrounding the nucleus, suspending organelles.

nDNA

Chromosomal DNA located in the nucleus; identical in each cell type (except red blood cells) within an organism.

Somatic cells

Body cells such as organs and tissues.

Diploid

A cell with a full complement of paired chromosomes (46 in humans).

Mitosis

A process where a single cell copies nuclear DNA (replication) and divides into 2 identical diploid daughter cells.

Gametes

Sex cells; sperm in males and ova/eggs in females.

Haploid

A cell with a single set of unpaired chromosomes (23 in humans).

Meiosis

A process involving one DNA replication and two cell divisions, creating 4 haploid gametic cells.

Crossing-over

The partial wrapping of homologous chromosomes around each other to exchange genetic information.

Recombination

The rearrangement of gene variants where maternal chromosomes gain paternal gene variants and vice versa.

Translocations

The exchange of segments between nonhomologous chromosomes, which can cause diseases and infertility.

Down syndrome

A condition caused by an extra copy of chromosome 21 joining chromosome 14.

Nondisjunctions

The failure of chromosomes to segregate, leading to gametes with abnormal numbers of chromosomes.

Monosomy

The loss in number of chromosomes.

Trisomy

The gain in number of chromosomes.

Mitochondria

ATP/energy-producing organelles that use oxygen to turn food molecules into ATP.

mtDNA

Mitochondrial DNA; 37 genes inherited from the mother.

Matriline

Lineage/inheritance that can be traced from mother to offspring.

Heteroplasmic

Presence of different/varying mtDNA among different parts of a person’s body or among the same kinds of cells.

Single nucleotide polymorphisms (SNPs)

Variations in DNA sequence due to the change of a single nitrogen base.

Transcription

One parental strand of DNA unzips, exposing 2 daughter strands of DNA, and free-floating RNA nucleotides match the daughter strand to move mRNA out of the nucleus into cytoplasm

Translation

mRNA enters cytoplasm, attaches to a ribosome, tRNA recognizes and binds with complementary base pairs of mRNA, and amino acids form a chain (polypeptide) through peptide bonds, allowing a “stop” codon for the protein to be completed

Methylation

Attachment of a methyl group (chemical) to DNA at certain sites.

Epigenetics

How the environment can result in heritable changes without alteration in the genome; represses the expression of certain genes.

Microsatellites

sequences of repeated base pairs of DNA, usually no more than 2-6, important when identifying bodies

Karyotype

Complete set of chromosomes for an individual organism/species (typically 23 pairs, 46 chromosomes).

Patriline

Lineage/inheritance traced from father to son via Y chromosome.

Autosomes

Nonsex chromosomes.

Structural genes

Genes coded to produce body structures (eg, hair, blood, other tissues), enzymes, and hormones.

Regulatory genes

Genes that determine when structural genes are turned on and off for protein synthesis.

Antigens

Proteins on the surfaces of cells that stimulate the immune system’s antibody production.

Antibodies

Part of the primary immune system, respond to foreign substances and attach to foreign antigens.

Codominant phenotypes

Two different alleles equally dominant (eg, AB blood type).

Pleiotropic

One gene has multiple biological effects.

Polygenic

One phenotypic trait affected by 2 or more genes.

Phenomes

The total set of phenotypic traits in an organism, influenced by genes and environmental factors.