Key Concepts in Genetics, Evolution, and Ecology

Gregor Mendel

Austrian biologist that made advances in genetics, mainly heredity using pea plants

Principles of dominance

Different versions of a gene/allele compete to determine traits

Law of segregation

States that alleles separate during mitosis so each gamete inherits only one allele per gene

Law of independent assortment

States that traits on different chromosomes are not inherited together. The inheritance of a trait on one chromosome does not control the inheritance of a different trait on a different chromosome

Punnett squares

Visual aid to determining phenotypes of different traits

Genes

Sections of DNA that are used to determine traits

Gametes

Mature haploid (sperm/egg) cell

Zygote

Diploid cell made by fusing of 2 opposite gametes

Human genetics

Study of how different traits are passed down through generations

Human disorders

Medical conditions that affect the functioning of the human body/mind

Chromosomes

Structure made of DNA and proteins found in the nucleus of the cell

Haploid cell

There are 23 in each haploid cell (46 in total/diploid)

Multiple alleles

When many genes exist in more than two forms

Incomplete dominance

Neither allele is dominant, results in a blending of the two traits (Ex: red and white flowers make pink flower)

Sex-linked inheritance

Traits determined by genes on sex chromosomes - certain sexes will have a trait, while the other doesn't (only in same family)

Codominance

2 alleles are competing for dominance, resulting in both traits being expressed (e.g. spotted cows)

Dominant trait

Characteristic that will be present if there is only one copy of the gene

Recessive trait

In order for trait to be expressed needs to have 2 copies of the gene

Genotype

Genetic makeup

Phenotype

Physical trait that results from the genotype

Homozygous

When 2 copies of the same allele are present

Heterozygous

2 different alleles

Transcription

RNA involvement: mRNA transcribes DNA code and takes it out of the nucleus to the ribosome; Where: nucleus

Translation

RNA involvement: rRNA provides structure and synthesizes proteins, and tRNA brings specific amino acids that correspond to the mRNA chain; Where: cytoplasm/ribosomes

Codon

Group of 3 nucleotides in mRNA that specifies a particular amino acid

Anticodon

Three unpaired bases, complementary to one mRNA codon

Mutations

Changes in genetic material

Point mutations

Changes in single nucleotides

Substitution

Point mutation in which one base is changed to a different base

Insertion

One or more nucleotides is added to the DNA sequence

Deletion

One or more nucleotides is removed from the DNA sequence

Natural selection

Organisms better suited to their environments are more likely to survive and reproduce

Galapagos finches/beak size

Darwin's evidence for this theory of natural selection

Gene variation

Differences in DNA sequences among individuals in a species or population

Effect on phenotype

Changes in the observable traits of an organism that make it better suited for the environment

Isolation

When species are isolated for long enough, they develop differently over time and eventually become different species

Binomial nomenclature

Naming a species for its Genus and species - universally understandable

Linnaeus

Biologist that popularized binomial nomenclature

Kingdoms

Bacteria, Plants, Protists, fungi, animals, archaea

Domains

Archaea, bacteria, eukarya

Prokaryote

Organisms without a nucleus/other organelles

Eukaryote

Clearly defined nucleus, has organelles, multicellular

Bacteria

Structure: Peptidoglycan cell walls, singular chromosome, cell membrane, prokaryotes; Parts: a cell wall, a cell membrane, cytoplasm, ribosomes, and genetic material (a nucleoid and/or plasmids)

E. Coli and salmonella

bacteria examples

Role of bacteria in environment

Decomposition, nutrient cycling, symbiotic relationships.

Virus

A microscopic infectious agent that can only replicate inside a host cell.

Structure of virus

Made of nucleic acid core with capsid/protein coat.

Lytic cycle

Virus enters cell, uses materials of host cell to make copies of its own DNA, viral DNA gets assembled into new capsids, infected cell lyses/bursts.

Lysogenic cycle

Virus integrates its DNA (prophage) into host cell's DNA, viral genetic info replicates along with DNA of host cell, viruses do not lyse host cell right away, lysogenic virus remains inactive for a period of time before entering the lytic cycle.

Disease

A condition that affects the structure/function of an organism.

Fungi

A kingdom of organisms that includes mushrooms and molds.

Structure of fungi

Chitin cell walls.

Role of fungi in environment

Decomposers.

Examples of fungi

Mushrooms, molds.

Ecology

The branch of biology that deals with the relations of organisms to one another and to their physical surroundings.

Symbiosis

Interaction between two different organisms living in close physical proximity.

Parasitism

When one organism benefits and the other is harmed.

Mutualism

When both organisms benefit.

Commensalism

When one organism benefits and the other is not affected.

Producer

An organism that can make its own food from organic compounds.

Consumer

Obtains energy from feeding on other organisms.

Decomposer

Breaks down dead organic matter for nutrients, also releases them back into ecosystem.

Keystone species

A species that the ecosystem would fall apart without - has a very large impact on the ecosystem while present.

Apex predator

An organism in an ecosystem that is at the top of the food chain; not preyed on by anything.

Carbon cycle

A system in which carbon travels through the environment.

Photosynthesis

A process in which plants use sunlight, water, and carbon dioxide to make food.

Respirations

Processes in which consumers use oxygen to make energy - carbon dioxide is a waste product.

Fossil fuels

Non-renewable energy sources formed underground by pressure and heat being put on ancient remains of plants and animals.

Chloroplast

An organelle in plants where photosynthesis occurs.

Thylakoids

Small discs in chloroplasts where the light dependent reactions occur.

Grana

Stacks of thylakoids.

Stroma

Fluid-filled space outside of thylakoids/grana - where light independent reactions occur in photosynthesis.