GCSE Biology - Inheritance, Variation and Evolution

Flashcards covering key concepts in GCSE Biology related to organisation.

DNA

A molecule that carries genetic information in cells.

Gene

A short section of DNA that codes for a specific protein.

Chromosome

A long DNA molecule found in the nucleus; humans have 23 pairs.

Genome

The entire set of genetic material in an organism.

Base pairs in DNA

A pairs with T, and C pairs with G.

mRNA

Carries the genetic code from DNA to ribosomes for protein synthesis.

Protein synthesis stages

1) Transcription (DNA to mRNA in the nucleus), 2) Translation (mRNA to protein at the ribosome).

Mutation

A change in the DNA sequence that may be harmless, affect protein function, or lead to disease.

Asexual reproduction

Reproduction with one parent, producing genetically identical offspring.

Sexual reproduction

Involves two parents; offspring are genetically varied, using gametes (egg and sperm).

Meiosis

Cell division that produces four genetically different gametes with half the chromosome number.

Allele

A different version of a gene.

Dominant allele

An allele that is expressed if present (only one copy needed).

Recessive allele

An allele that is only expressed if two copies are present.

Genotype

The genetic makeup of an organism (e.g. Bb).

Phenotype

The physical characteristics expressed by an organism (e.g. brown eyes).

Homozygous

Two identical alleles (BB or bb).

Heterozygous

Two different alleles (Bb).

Polydactyly

An inherited disorder causing extra fingers or toes, caused by a dominant allele.

Cystic fibrosis

A disorder of cell membranes caused by a recessive allele.

Genetic disorders detection

Can be detected through embryo screening and family history.

Benefits of embryo screening

Prevents suffering, reduces healthcare costs, helps parents prepare.

Disadvantages of embryo screening

May lead to discrimination, ethical concerns, and expense.

Variation in a population

Caused by genetic differences, environment, or a combination of both.

Evolution

Gradual change in species over time due to natural selection.

Natural selection

The process where the best-adapted individuals survive and reproduce.

Selective breeding

Humans breeding plants or animals for desired characteristics.

Genetic engineering

Changing an organism's DNA to include desirable genes.

GM crops

Genetically modified crops that may be resistant to disease or pests, or contain more nutrients.

Pros of GM crops

Increased yield, reduced pesticide use.

Cons of GM crops

Possible long-term effects, ethical concerns.

Types of cloning

Tissue culture, cuttings (plants), embryo transplants, and adult cell cloning.

Adult cell cloning

Nucleus from an adult cell inserted into an empty egg cell, stimulated to divide and develop.

Issues with cloning

Ethical concerns, low success rate, lack of genetic variation.

Fossils

Remains of organisms from millions of years ago found in rocks.

Fossil formation

From parts not decayed, mineral replacement, or preserved traces.

Incomplete fossil record

Because many organisms didn't fossilise, or fossils have been destroyed.

Causes of extinction

New predators, diseases, competition, environmental changes, catastrophic events.

Antibiotic resistance development

Random mutations make bacteria resistant, enabling them to survive and reproduce.

Danger of antibiotic resistance

Infections become harder to treat; superbugs like MRSA emerge.

Reducing antibiotic resistance

Avoid overusing antibiotics, complete courses, develop new antibiotics.

Classification

Organising organisms based on similarities and differences.

Linnaean system

A hierarchical classification system consisting of Kingdom, Phylum, Class, Order, Family, Genus, Species.

Three-domain system

Classifies organisms into Archaea, Bacteria, Eukaryota based on genetic analysis.

Species

A group of organisms that can interbreed and produce fertile offspring.