Grade 12 Life Sciences: DNA, Meiosis, and Human Reproduction

Vocabulary-style flashcards covering the fundamental biological terms from the Grade 12 Life Sciences textbook transcript, focusing on genetics, meiosis, and reproduction.

DNA

Deoxyribonucleic acid; the nucleic acid that carries the genetic code for protein synthesis and hereditary information.

Double Helix

The spiral-ladder shape of DNA consisting of two strands joined by weak hydrogen bonds.

Nucleotide

The monomer (building block) of nucleic acids, consisting of a phosphate group, a sugar molecule, and a nitrogenous base.

Nuclear DNA

DNA found specifically within the nucleus of a cell.

Extra-nuclear DNA

DNA found outside the nucleus, specifically in mitochondria (mtDNA) or chloroplasts.

RNA

Ribonucleic acid; a single-stranded nucleic acid containing ribose sugar and the nitrogenous base uracil instead of thymine.

mRNA

Messenger RNA; carries the genetic code from DNA in the nucleus to the ribosomes in the cytoplasm.

tRNA

Transfer RNA; picks up specific amino acids in the cytoplasm and brings them to the ribosome for protein synthesis.

DNA Replication

The process occurring during interphase where DNA makes an identical copy of itself to ensure daughter cells have the same genetic info.

Transcription

The first stage of protein synthesis where a complementary mRNA strand is formed from a DNA template in the nucleus.

Translation

The second stage of protein synthesis where amino acids are linked in a specific sequence at the ribosome to form a protein.

Meiosis

A type of cell division that halves the chromosome number from diploid to haploid to produce genetically different gametes.

Chromatid

One of two identical strands of a replicated chromosome, held together by a centromere.

Crossing Over

The exchange of genetic material between chromatids of homologous chromosomes during Prophase I of meiosis.

Haploid (n)

A cell containing only one complete set of chromosomes, such as a gamete.

Diploid (2n)

A cell containing two complete sets of chromosomes, one from each parent.

Non-disjunction

The failure of homologous chromosomes or sister chromatids to separate during meiosis, which can lead to disorders like Down Syndrome.

Ovipary

A reproductive strategy where eggs are laid and the embryo develops outside the mother's body.

Vivipary

A reproductive strategy where the young develop inside the mother's uterus and receive nourishment through a placenta.

Amniotic Egg

An egg protected by a shell and extra-embryonic membranes, allowing animals to reproduce on land without water.

Gestation

The period of development of an embryo/foetus in the uterus between fertilisation and birth.

Allele

Different forms of a gene located at the same locus on homologous chromosomes.

Genotype

The genetic composition of an organism, represented by pairs of alleles (e.g., Tt).

Phenotype

The physical appearance of an organism based on its genotype (e.g., Tall).