HSC Biology Module 5: Heredity Vocabulary

Comprehensive vocabulary covers mechanisms of reproduction, mammalian pregnancy hormones, agricultural practices, DNA replication, and inheritance patterns.

Fertilisation

The fusion of two haploid gametes to form a diploid zygote.

External Fertilisation

A reproductive mechanism where fertilisation occurs outside of the organism’s body, common in organisms such as frogs and fish.

Internal Fertilisation

A reproductive mechanism where male gametes are introduced into the female body via copulation to reach the female gametes.

Oviparous

A type of internal fertilisation found in reptiles and birds where a fertilised egg is laid and development occurs outside the mother's body.

Viviparous

A type of internal fertilisation found in mammals where development occurs inside the mother and she gives birth to live offspring.

Vegetative Propagation

A form of asexual reproduction in plants where new individuals are cloned from a part of the adult, such as bulbs or tubers.

Perennating organs

Underground structures such as roots or stems that store food to help a plant survive adverse conditions, ensuring continuity.

Runners

Modified stems that grow along the surface of the soil to produce new plants, such as in strawberries.

Rhizomes

Modified underground stems used for asexual reproduction, typical in grasses.

Suckers

Modified roots used for asexual reproduction in plants like wattles and blackberries.

Pollination

The process of transporting pollen from the male parts of a plant to the female stigma.

Budding

An asexual method where a small growth develops on the adult organism and eventually separates to become an independent, genetically identical individual.

Spores

Tiny unicellular reproductive cells produced by fungi that are light and spread by wind to colonise new environments.

Binary Fission

A method of asexual reproduction where a cell replicates its DNA, grows to twice its size, and splits into two genetically identical daughter cells.

Implantation

The process where a blastocyst attaches to and burrows into the uterine wall (endometrium).

Morula

A ball of unspecialised embryonic STEM cells formed around day 3-4 after fertilisation.

Blastocyst

An embryonic stage occurring around day 5-7 where differentiation begins, forming an internal cell mass (embryo) and an external layer (placenta).

Gestation

The period of development of offspring inside the womb between conception and birth, lasting approximately $40$ weeks in humans.

FSH (Follicle Stimulating Hormone)

A hormone from the pituitary gland that causes the egg to mature in the ovary and stimulates the release of oestrogen.

Oestrogen

A hormone that repairs and maintains the uterus lining, inhibits FSH, and stimulates the pituitary gland to release LH.

LH (Luteinising Hormone)

A hormone from the pituitary gland that triggers ovulation, the release of a mature egg.

Progesterone

A hormone produced by the ovaries and placenta that maintains the uterus lining and inhibits uterine contractions during pregnancy.

hCG (Human Chorionic Gonadotropin)

A hormone produced by the placenta after implantation that supports the corpus luteum and is detected by pregnancy tests.

Relaxin

A hormone produced by the placenta that inhibits contractions, relaxes blood vessels, and softens the cervix during birth.

Oxytocin

A hormone that stimulates contractions of the uterine muscle and triggers the production of prostaglandins during labour.

DNA Polymerase III

An enzyme that builds new DNA strands by adding complementary nucleotides in the $5'-3'$ direction.

Helicase

The enzyme responsible for unzipping the DNA double helix by breaking the hydrogen bonds between base pairs.

Ligase

An enzyme that acts as "glue" to join together Okazaki fragments on the lagging strand.

Okazaki fragment

Short fragments of DNA produced on the lagging strand during DNA replication.

Introns

Non-coding DNA sequences within a gene that are removed during splicing and are not expressed as proteins.

Exons

The sections of a gene that code for traits and are expressed in the organism.

Crossing over

The exchange of alleles between non-sister chromatids on homologous chromosomes during Prophase I of meiosis.

Independent assortment

The process during Metaphase I where genes and alleles for different traits are inherited independently of one another.

Random Segregation

The random and equal separation of alleles into daughter cells during Anaphase I and II.

Co-dominance

A condition in which two alleles are both expressed in the phenotype, such as in roan cattle.

Incomplete dominance

A form of inheritance where the heterozygous phenotype is a blend of the two homozygous phenotypes, such as pink snapdragons.

SNPs (Single Nucleotide Polymorphisms)

Point mutations that occur in more than $1\%$ of the population, often used for relation testing and disease association.

DNA sequencing

A technique used to determine the precise order of nucleotides (A, T, C, G) in a DNA sample.

PCR (Polymerase Chain Reaction)

A technique used to amplify and make many copies of a specific DNA section.

Gel Electrophoresis

A laboratory method used to separate DNA fragments based on their length by migrating them through a gel using an electric current.

STRs (Short Tandem Repeats)

Short sections of DNA with repeating nucleotide sequences used as genetic markers in DNA profiling.

Transcription

The process in the nucleus where the information in a DNA sequence is copied into a complementary mRNA strand.

Translation

The process at the ribosome where the mRNA code is used to assemble amino acids into a polypeptide chain.

Codon

A trinucleotide sequence of mRNA that corresponds to a specific amino acid or a start/stop signal.

Methylation

An epigenetic mechanism where a methyl group ($CH_3$) attaches to DNA and inhibits gene expression.

Acetylation

An epigenetic mechanism where an acetyl group ($COCH_3$) attaches to histones and increases gene expression.