Heredity & Genetics – Module 5 Vocabulary

A comprehensive set of key vocabulary flashcards covering reproduction strategies, DNA structure and replication, cell division, protein synthesis, and patterns of genetic inheritance for Module 5.

Reproduction

Biological process by which organisms produce offspring, ensuring the continuity of a species.

Reproductive Success

An organism’s ability to produce fertile offspring that survive to reproduce.

Biological Fitness

Measure of an individual’s reproductive success in passing on its genes.

Allele

Alternative form of a gene found at the same locus on a chromosome.

Asexual Reproduction

Production of offspring from a single parent without gamete fusion; offspring are genetically identical to the parent.

Sexual Reproduction

Production of offspring through the fusion of male and female gametes during fertilisation, creating genetic variation.

Gamete

Sex cell (sperm or egg) with a haploid set of chromosomes.

Fertilisation

Fusion of male and female gametes to form a zygote.

Internal Fertilisation

Fertilisation that occurs inside the body of an organism, typical of terrestrial species.

External Fertilisation

Fertilisation that occurs outside the bodies of the parents, usually in aquatic environments.

Oviparous

Describes animals that lay fertilised eggs which develop and hatch outside the mother’s body.

Viviparous

Describes animals whose embryos develop inside the mother and are born alive.

Ovoviviparous

Reproductive mode where fertilised eggs develop inside the mother and hatch just before or after they are laid.

Hermaphrodite

Individual possessing both male and female reproductive organs.

Embryonic Diapause

Temporary pause in embryo development to align birth with favourable conditions.

Eutherian

Placental mammal in which the developing fetus is nourished via a placenta.

Pollination

Transfer of pollen from anther to stigma in flowering plants.

Self-Pollination

Pollination involving pollen and ovules from the same plant; requires less energy.

Cross-Pollination

Pollination involving pollen transfer between different plants, increasing genetic diversity.

Germination

Process by which a plant embryo within a seed resumes growth to form a seedling.

Seed Dispersal

Spread of seeds away from the parent plant to reduce competition and increase survival chances.

Binary Fission

Asexual reproduction in which a cell copies its DNA and splits into two identical daughter cells.

Budding

Asexual reproduction where a new organism grows from a small outgrowth of the parent.

Sporogenesis

Formation of spores that can develop into new individuals without fertilisation.

Fragmentation

Asexual reproduction where a parent organism splits into parts, each growing into a new individual.

Parthenogenesis

Development of an unfertilised egg into a new organism containing only maternal genes.

Vegetative Propagation

Asexual reproduction in plants via new shoots, runners or tubers forming complete plants.

DNA (Deoxyribonucleic Acid)

Double-helical molecule storing hereditary information in the sequence of nitrogenous bases.

Chromosome

Package of DNA wrapped around histone proteins; carries genetic information.

Mitosis

Cell division producing two genetically identical daughter cells for growth and repair.

Meiosis

Two-stage cell division producing four genetically unique haploid gametes.

Pluripotent Cell

Stem cell capable of differentiating into many cell types.

Meristem

Region in plants containing pluripotent stem cells responsible for growth.

Interphase

Cell-cycle phase of growth and DNA replication (G1, S, G2).

Prophase

First mitotic stage where chromosomes condense and the nuclear membrane breaks down.

Metaphase

Mitotic stage in which chromosomes align at the cell equator.

Anaphase

Mitotic stage where sister chromatids separate to opposite poles.

Telophase

Final mitotic stage in which chromosomes decondense and nuclei re-form.

Cytokinesis

Division of cytoplasm, producing two separate daughter cells.

Helicase

Enzyme that unwinds and separates DNA strands during replication.

Primase

Enzyme that synthesises RNA primers for DNA polymerase during replication.

DNA Polymerase

Enzyme that adds complementary nucleotides to a growing DNA strand and proofreads for errors.

Ligase

Enzyme that seals nicks in the sugar-phosphate backbone, joining DNA fragments.

Watson–Crick Model

Description of DNA as a double helix with complementary base pairing (A–T, G–C).

Antiparallel

Orientation of the two DNA strands running in opposite 5′→3′ directions.

Mutation

Permanent change in DNA sequence; may arise from replication errors.

Transcription

Synthesis of RNA from a DNA template in the nucleus.

RNA Polymerase

Enzyme that builds an RNA strand complementary to a DNA template during transcription.

mRNA (Messenger RNA)

RNA copy of a gene that carries coding information to the ribosome.

Codon

Triplet of mRNA bases specifying a particular amino acid or stop signal.

tRNA (Transfer RNA)

RNA molecule that carries a specific amino acid and has an anticodon complementary to an mRNA codon.

Anticodon

Set of three bases on tRNA that pairs with a codon on mRNA.

Translation

Process at the ribosome where amino acids are linked into a polypeptide according to mRNA codons.

Start Codon

mRNA codon AUG (methionine) that initiates translation.

Polypeptide

Chain of many amino acids linked by peptide bonds; folds to become a protein.

Genotype

Genetic makeup of an organism for a particular trait or set of traits.

Phenotype

Observable characteristics of an organism resulting from genotype and environment.

Globular Protein

Compact, spherical protein that is typically soluble (e.g., enzymes).

Fibrous Protein

Elongated, insoluble protein providing structural support (e.g., collagen).

Primary Structure

Linear sequence of amino acids in a polypeptide chain.

Secondary Structure

Local folding of a polypeptide into α-helices or β-pleated sheets.

Tertiary Structure

Overall three-dimensional shape of a single polypeptide chain.

Quaternary Structure

Association of multiple polypeptide subunits into a functional protein complex.

Genetic Variation

Differences in DNA sequences among individuals in a population.

Bivalent

Pair of homologous chromosomes aligned during prophase I of meiosis.

Chiasma (plural Chiasmata)

Point where non-sister chromatids exchange genetic material during crossing over.

Mendel’s Law of Segregation

Each individual has two alleles for a trait, and gametes carry only one allele.

Mendel’s Law of Independent Assortment

Alleles of different genes assort independently during gamete formation if on separate chromosomes.

Codominance

Inheritance pattern where both alleles in a heterozygote are fully expressed (e.g., roan cattle).

Incomplete Dominance

Inheritance pattern where heterozygotes display an intermediate phenotype (e.g., pink snapdragons).

Sex Linkage

Inheritance of genes located on sex chromosomes, often showing different patterns in males and females.

Autosomal

Referring to genes located on non-sex chromosomes (autosomes).

Multiple Alleles

More than two alternative forms of a gene exist in a population (e.g., ABO blood group).

Punnett Square

Grid diagram showing potential genotypes of offspring from parental crosses.

Pedigree Chart

Family tree diagram showing inheritance patterns of a trait across generations.

Mitosis: Stages

A cell division process for growth and repair, producing two diploid (2n) genetically identical daughter cells. It includes:

1. Interphase: Cell growth, DNA replication (G1, S, G2).
2. Prophase: Chromosomes condense, nuclear membrane breaks down.
3. Metaphase: Chromosomes align at the cell equator.
4. Anaphase: Sister chromatids separate to opposite poles.
5. Telophase: Chromosomes decondense, nuclei re-form.
6. Cytokinesis: Cytoplasm divides, forming two daughter cells.

Meiosis: Stages and Genetic Outcomes

A two-stage cell division producing four haploid (n) genetically unique gametes from a diploid (2n) parent cell. Critical for sexual reproduction and genetic diversity.

1. Meiosis I (Reductional Division): Homologous chromosomes separate.
   • Homologous chromosomes pair to form bivalents; chiasmata form, allowing genetic exchange (crossing over) in prophase I.
   • Homologous pairs align, then separate to opposite poles, reducing chromosome number by half.
2. Meiosis II (Equational Division): Sister chromatids separate.
   • Similar to mitosis, sister chromatids in each haploid cell separate, resulting in four haploid, genetically distinct daughter cells.

Sexual Reproduction: Advantages and Disadvantages

Production of offspring through the fusion of male and female gametes during fertilisation, creating genetic variation.

• Advantages: Increased genetic diversity, higher adaptability to changing environments, allowing for evolution.
• Disadvantages: Requires two parents, slower process, requires more energy for mate finding and courtship, typically produces fewer offspring.

Asexual Reproduction: Advantages and Disadvantages

Production of offspring from a single parent without gamete fusion; offspring are genetically identical to the parent.

• Advantages: Requires only one parent, faster reproduction, less energy required, rapid colonization of new environments.
• Disadvantages: Lack of genetic diversity, offspring are susceptible to the same diseases or environmental changes as the parent, limited adaptability to changing conditions.

Internal Fertilisation: Advantages and Disadvantages

Fertilisation that occurs inside the body of an organism.

• Advantages: Gametes protected from desiccation (drying out) and predation, higher chance of successful fertilisation, often higher offspring survival rates, especially for terrestrial species.
• Disadvantages: Requires proximity of mates, fewer offspring produced compared to external fertilisation, energy investment in parental care might be higher.

External Fertilisation: Advantages and Disadvantages

Fertilisation that occurs outside the bodies of the parents, usually in aquatic environments.

• Advantages: Requires less energy for mate finding, allows for broad dispersal of gametes and offspring, large number of offspring can be produced.
• Disadvantages: Gametes and embryos are vulnerable to environmental hazards (e.g., predation, desiccation, temperature changes), lower chance of fertilisation success per gamete, often lower offspring survival rates, limited to aquatic or very moist environments.