Biology Vocabulary Flashcards - Reproduction, Genetics, Cells, Immunity, Disease & Biotechnology

Vocabulary flashcards covering key terms from reproduction, genetics, cell biology, immunology, disease transmission, biotechnology, and homeostasis.

Fertilisation

The fusion of sperm and egg gametes in sexual reproduction.

External fertilisation

Fertilisation that occurs when gametes meet in the external environment, usually in water.

Internal fertilisation

Fertilisation that occurs inside the female body, after copulation.

Oviparous

Development occurs outside the mother in eggs laid in the environment.

Viviparous

Development occurs inside the mother with live birth.

Ovoviviparous

Egg develops inside the mother and hatches there, giving birth to live young.

Asexual reproduction

Reproduction that does not involve fertilisation and yields genetically identical offspring.

Fragmentation

A form of asexual reproduction where new plants grow from fragments of the parent.

Vegetative propagation

Asexual plant reproduction from non-sexual structures or fragments.

Stolons

Horizontal stems that form new plants at nodes (e.g., strawberries).

Rhizomes

Underground stems with nodes that generate shoots and roots (e.g., seagrass).

Tubers

Thickened underground stems storing nutrients that can give rise to new plants (e.g., potato).

Bulbs

Underground storage organs with fleshy leaves that nourish during dormancy.

Suckers

Growth from the rootstock that forms new shoots (e.g., banana plants).

Pollination

Transfer of pollen from anther to stigma, enabling fertilisation.

Self-pollination

Pollination within the same plant, producing less genetic variation.

Cross-pollination

Pollination between different plants, increasing genetic variation.

Pollen tube

A tube that grows from a pollen grain to the ovule to deliver sperm cells.

Gametes

Male and female reproductive cells (sperm and egg) in sexual reproduction.

Zygote

Diploid cell formed by fertilisation of an egg by a sperm.

Morula

Early embryo—solid ball of cells after several divisions.

Blastocyst

Hollow, fluid-filled ball of cells that implants into the uterus.

Implantation

Process by which the blastocyst embeds in the endometrium.

Endometrium

Uterine lining that thickens in preparation for implantation.

Placenta

Maternal–fetal exchange organ that transports nutrients and wastes.

Corpus luteum

Temporary endocrine structure that secretes progesterone after ovulation.

Progesterone

Hormone that regrows/thickens the uterine lining to support pregnancy.

Estrogen

Hormone that promotes endometrial thickening and secondary sex characteristics.

hCG (human chorionic gonadotropin)

Hormone that sustains the corpus luteum and progesterone production during pregnancy.

Fertilisation site (external vs internal)

Location where fertilisation occurs: in water (external) or within the female reproductive tract (internal).

Meiosis

Cell division producing four haploid gametes from a diploid cell; includes crossing over.

Mitosis

Cell division producing two identical diploid daughter cells for growth/repair.

Crossing over

Exchange of genetic material between non-sister chromatids in meiosis I.

Independent assortment

Random orientation of chromosome pairs during Metaphase I, increasing variation.

Random segregation

Separation of homologous chromosomes or sister chromatids during meiosis II.

DNA replication

Semi-conservative copying of DNA, producing two double strands.

Topoisomerase

Enzyme that relieves supercoiling ahead of the replication fork.

Helicase

Enzyme that unwinds the DNA double helix at the replication fork.

Primase

Enzyme that lays down RNA primers to start DNA synthesis.

DNA polymerase III

Main enzyme that adds nucleotides to form a new DNA strand.

Leading strand

DNA strand synthesised continuously toward the replication fork.

Lagging strand

DNA strand synthesised discontinuously as Okazaki fragments away from the fork.

Okazaki fragment

Short DNA fragment synthesised on the lagging strand.

Ligase

Enzyme that seals nicks between DNA fragments to form a continuous strand.

Transcription

Process of copying DNA into messenger RNA (mRNA) in the nucleus.

Translation

Process of decoding mRNA to synthesize a protein at the ribosome.

Codon

Three-nucleotide sequence in mRNA coding for a specific amino acid.

Anticodon

Three-nucleotide sequence on tRNA that pairs with a codon.

mRNA

Messenger RNA; carries genetic code from DNA to ribosome for protein synthesis.

tRNA

Transfer RNA; brings specific amino acids to the ribosome during translation.

Ribosome

Cellular organelle where translation occurs.

Polypeptide

A chain of amino acids that folds into a protein.

Protein

Functional macromolecule made of one or more polypeptides.

Genotype

The genetic makeup of an organism—the alleles present.

Phenotype

Visible or measurable traits determined by genotype and environment.

Allele

Different versions of a gene.

Homozygous

Two identical alleles at a gene locus.

Heterozygous

Two different alleles at a gene locus.

Autosomal inheritance

Gene inheritance on autosomes (non-sex chromosomes).

Sex-linked inheritance

Genes located on sex chromosomes, often X-linked.

Codominance

Both alleles of a gene are fully expressed in the phenotype.

Incomplete dominance

Heterozygote expresses an intermediate phenotype.

Multiple alleles

More than two allele forms exist for a gene (e.g., ABO blood groups).

Punnett square

Tool to predict offspring genotypes from parental crosses.

Hardy-Weinberg equilibrium

Allele and genotype frequencies remain constant in a non-evolving population.

SNP

Single nucleotide polymorphism; a common DNA sequence variation.

GWAS

Genome-wide association study; identifies SNPs linked to diseases.

DNA sequencing

Determining the exact order of nucleotides in DNA.

PCR

Polymerase chain reaction; method to amplify DNA segments.

Gel electrophoresis

Technique to separate DNA fragments by size using an electric field.

Restriction enzyme

Enzyme that cuts DNA at specific sequences.

Plasmid

Circular DNA molecule used as a vector in genetic engineering.

Transformation

Introduction of plasmid DNA into a bacterial cell.

Recombinant DNA

DNA created by combining DNA from different sources.

Bt crops

Transgenic crops expressing Bacillus thuringiensis insecticidal protein.

CRISPR-Cas9

Genome editing system using guide RNA and Cas9 enzyme to modify DNA.

Transgenic organism

Organism carrying genes from another species due to genetic modification.

Cloning

Creating genetically identical copies; includes whole-organism and gene cloning.

SCNT

Somatic cell nuclear transfer; cloning method used in Dolly the sheep.

Embryo splitting

Cloning method yielding two embryos from one embryo.

Heredity

Passing of traits from parents to offspring through genes.

Mutation

Permanent change to the DNA sequence.

Point mutation

Change of a single base in DNA; includes substitutions, insertions, deletions.

Substitution

Replacement of one base with another in DNA.

Insertion

Addition of a base or bases into DNA.

Deletion

Removal of a base or bases from DNA.

Frameshift mutation

Mutation that shifts the reading frame, altering downstream codons.

Missense mutation

A base change that alters an amino acid codon.

Nonsense mutation

A mutation that creates a premature stop codon.

Silent mutation

A mutation that does not change the amino acid sequence.

Chromosomal mutation

Large-scale changes in chromosome structure or number (e.g., translocation, inversion).

Aneuploidy

Abnormal number of chromosomes (e.g., trisomy 21).

Polyploidy

More than two complete chromosome sets in an organism.

Karyotype

Number and appearance of chromosomes in a cell.

Genetic drift

Random changes in allele frequencies, especially in small populations.

Gene flow

Movement of genes between populations via migration.

Bottleneck effect

Sharp reduction in population size altering allele frequencies.

Founder effect

Genetic drift when a new population is founded by a small group.

Hardy-Weinberg equation

p^2 + 2pq + q^2 = 1 describes genotype frequencies from allele frequencies p and q.

Population genetics

Study of genetic variation within populations and how it changes over time.