Arrangement of Genetic Information and Evolution Review

Comprehensive flashcards covering the arrangement of genetic information, DNA structure, cell division (mitosis and meiosis), inheritance, genetic technologies, and the theory of evolution by natural selection.

Genome

The blueprint unique to you containing all the instructions for your genetic traits from your mother and father; it is the complete set of all DNA in an organism.

DNA (deoxyribonucleic acid)

A twisted ladder called a double helix that stores all our biological instructions, located in the nucleus of nearly every cell.

Nucleotide

The basic unit of DNA consisting of a phosphate group, a five-carbon sugar, and a nitrogen-containing base.

Nitrogenous Bases

The four chemical bases in DNA: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).

Gene

A specific segment or section of DNA that acts as the basic functional unit of heredity and codes for proteins.

Proteins

The basic building blocks for our bodies used to repair and make new tissue, chemical messengers like hormones, and antibodies.

Genotype

The specific genetic code for an organism.

Phenotype

The visible traits or expressed characteristics of an organism, such as height, hair colour, or blood type.

Chromosome

Packaged, tightly coiled DNA that typically forms an x-shape in eukaryotes; humans normally have 23 pairs (46 total).

Chromatid

One of two identical parts of a chromosome, made up of one long DNA molecule joined with its twin at the centromere.

Histones

Small protein balls that DNA wraps around to ensure effective coiling and packing.

Plasmids

Circular chromosomes found in simple prokaryotic organisms.

RNA (ribonucleic acid)

A single-stranded molecule containing ribose sugar and uracil ($U$) instead of thymine, which helps DNA replicate and produce proteins.

Covalent Bonds

Strong chemical bonds that join the sugar and phosphate molecules in the DNA backbone to keep the strand stable.

Hydrogen Bonds

Weaker chemical bonds that join complementary nitrogen bases, allowing DNA strands to separate for replication or transcription.

DNA helicase

The enzyme that breaks hydrogen bonds and unzips the DNA during replication.

DNA polymerase

The enzyme that adds matching nucleotides using base-pair rules to form new DNA strands.

Daughter molecules

The two identical double-helix DNA molecules formed after DNA replication, each consisting of one original and one new strand.

Transcription

The process where a section of DNA containing a specific gene unwinds and is copied into messenger RNA (mRNA).

Translation

The process where mRNA attaches to a ribosome, which reads the sequence of nitrogenous bases to form a chain of amino acids.

Amino Acids

The building blocks that join together to form a protein polymer.

Enzymes

Proteins that speed up chemical reactions in cells, such as amylase for starch or lactase for milk sugar.

Okazaki fragment

Short DNA segments built discontinuously on the lagging strand during replication.

DNA ligase

An enzyme that attaches or ligates DNA nucleotides together to complete the synthesis of the lagging strand.

James Watson and Francis Crick

Scientists who presented the double helix model of DNA in the 1950s.

Rosalind Franklin

A chemist whose X-ray photography, specifically Photograph 51, provided evidence of the double helix structure of DNA.

Maurice Wilkins

A physicist who proposed using X-rays to photograph DNA and shared the 1962 Nobel Prize with Watson and Crick.

Friedrich Miescher

A Swiss chemist who first discovered DNA in 1869, originally calling it nuclein.

Phoebus Levene

A biochemist who proposed in 1919 that nucleic acids were composed of nucleotides made of a base, phosphate, and sugar.

Erwin Chargaff

A biochemist who discovered that the order of nucleotides is varied and that the amount of adenine equals thymine, and cytosine equals guanine.

Mitosis

The process by which body cells divide to form two identical daughter cells for growth and repair.

Meiosis

A type of cell division that produces four genetically unique haploid gametes (sex cells).

Prophase

The first stage of mitosis where chromosomes condense and become visible, the nuclear membrane breaks down, and spindle fibres form.

Metaphase

The stage of mitosis where chromosomes line up at the equator of the cell and spindle fibres attach.

Anaphase

The stage where sister chromatids separate and are pulled to opposite ends of the cell.

Telophase

The final stage where new nuclei form and chromosomes uncoil.

Cytokinesis

The division of the cytoplasm that follows mitosis, resulting in two separate cells.

Diploid

Cells containing two full sets of chromosomes ($46$ in humans).

Haploid

Cells containing one set of chromosomes ($23$ in human gametes).

Binary fission

A form of asexual reproduction used by single-celled organisms like bacteria to split into two identical cells.

Crossing over

The process during meiosis where homologous chromosomes swap sections of genetic code, creating genetic variation.

Zygote

The fertilised egg cell formed when a sperm and egg combine, restoring the diploid chromosome number.

Ovaries

Female reproductive organs that produce eggs (ova) and the hormones oestrogen and progesterone.

Fallopian tubes

The tubes that carry the egg from the ovary to the uterus and serve as the usual site of fertilisation.

Uterus

A muscular organ where a fertilised egg implants and develops into an embryo.

Testes

Male reproductive organs located in the scrotum that produce sperm and testosterone.

Epididymis

The structure where sperm are stored and mature to gain the ability to swim.

Prostate gland

A gland that adds fluid to sperm to form semen and helps neutralise the acid from the vagina.

Alleles

Different forms or variations of a specific gene.

Dominant allele

An allele that only requires one copy for the trait to appear in the phenotype.

Recessive allele

An allele that requires two copies for the trait to appear; it is masked by a dominant allele.

Homozygous

A genotype with two identical alleles (e.g., $AA$ or $aa$).

Heterozygous

A genotype with two different alleles (e.g., $Aa$).

Gregor Mendel

A scientist who studied inheritance patterns in pea plants and determined that traits are passed down in predictable 3:1 ratios.

Punnett Square

A diagram used to show the possible genotypes of offspring from a set of parents.

Pedigree Chart

A chart that shows the inheritance of a trait through multiple generations of a family.

Biotechnology

The use of living things to develop or modify products for fields like farming and medicine.

Whole organism cloning

A technology where DNA from a donor cell is placed into an enucleated egg cell, resulting in a genetically identical organism (e.g., Dolly the sheep).

Recombinant DNA

DNA formed by inserting a target gene from one organism into a bacterial plasmid to create mass copies or transgenic organisms.

Transgenic organisms

Organisms that have had their genetic code altered by the insertion of genes from another species, such as BT cotton or Golden rice.

Gene therapy

A technology used to manage or cure genetic diseases by introducing healthy genes into human cells.

Natural selection

The process by which organisms with beneficial traits better suited to their environment are more likely to survive and reproduce.

Selection pressures

Environmental factors such as competition, predation, and climate change that influence which individuals survive.

Absolute dating

Determining the age range of a fossil or object in actual numbers of years, often through radioactive decay.

Relative dating

Arranging fossils or rocks in sequence from oldest to youngest based on their position in rock layers.

Biogeography

The study of the past and present distribution of living organisms, providing evidence for continental drift and evolution.

Homologous structures

Features in different species that are similar in structure but different in function, indicating a common ancestor (e.g., human arm and whale fin).

Vestigial structure

A feature of an organism that has lost some or all of its function through evolution, such as the human tailbone.

Comparative embryology

The study of the similarity of embryos of different species during development as evidence of shared ancestry.

HeLa cells

Immortal cancer cells taken from Henrietta Lacks in 1951 that divide continuously and are used extensively in medical research.

CRISPR

A genetic technology that allows scientists to cut DNA at specific locations to remove, replace, or add genetic material.