Bio December Exam Terms

Some, not all key terms

Catalysis

To give control over which chemical reactions occur

Self Assembly

Carbon compounds such as amino acids must assemble to form polymers

Compartmentalization

A membrane must develop to enclose cell contents

Self Replication of Molecules

As a basis for inheritance and the persistence of successful variants

Vesicles

Small droplets of fluid enclosed in membrane, very common structures inside cells

Convergent Evolution

Strikingly similar structures to evolve in organisms that do not have a recent common ancestor

LUCA

Last universal common ancestor

Magnification

Size of Image ÷ Actual Size of Specimen

Fluorescence

When a substance absorbs light and then re-emits it at a longer wavelength. Fluorescent stains have been used for 100 years

Immunofluorescence

A development of fluorescent staining

Plasma Membrane

Outer boundary of cell, encloses all its contents, controls entry and exit of substances

Lysis

When plasma membrane of cell bursts, can be caused by excess pressure or viruses. Always leads to cell death as the plasma membrane is vital.

Cytoplasm

Water is main component, many substances dissolved/suspended in water, enzymes in [blank] = chemical reactions (metabolism of cell). [blank] replaces cell’s proteins.

DNA

Contain information needed for cell to carry out its functions, many genes hold instructions for making proteins, others can act as enzymes

Nucleus

Has double membrane, holds cell’s chromosomes, each one consisting of a long DNA molecule attached to proteins (except for when cell is dividing then the DNA is replicating)

80S Ribosomes

Ribosomes in eukaryotic cells synthesize proteins, as in prokaryotes. The difference is their structure and they are longer in size

Mitochondria

Cytoplasm of eukaryotic cell contains [blank], which carries out aerobic cell respiration. Is surrounded by double membrane

Homeostasis

Maintenance of a constant internal environment in an organism

Mechanism living things have for maintaining equilibrium

Metabolism

The sum of all the biochemical reactions that occur in a living organism

Nutrition

Supplying the nutrients required for energy, growth and repair in an organism

Excretion

Removal of waste products of metabolism from an organism

Growth

An increase in size/number of cells

Response to Stimuli

Perception of stimuli and carrying out appropriate actions in response

Reproduction

Production of offspring, either sexually/asexually

Vital Processes in Living Organisms

Happy Monkeys Never Eat Green Rotten Raisins

Plastids

Family of organelles with 2 outer membranes and internal membrane sacs

Cell Wall

Rigid layer outside plasma membrane to strenghten and protect cell

Vacuoles

Flexible fluid-filled compartment surrounded by single membrane

Centrioles

Cylindrical organelles that organize the assembly of structures composed of microtubules

Undulipodia

Cilia and flagella used to generate movement of a cell or movement of fluid adjacent to a cell

Red Blood Cells

In mammals, have no nucleus — makes them smaller, more flexible but can’t repair themselves when damaged (lifespan: 100-120 days)

Phloem Sieve Tube Elements

Phloem = sap from leaves that is transported to other parts of organism
Xylem = water from roots that is transported to the leaves

Skeletal Muscle

Groups of cells fuse together (synctium), forming long muscle fibres

Aseptate Fungal Hyphae

In some cells nucleus divides repeatedly without cell division = unusually large multinucleate structure

Lysogenic Cycle

Viral DNA becomes integrated into bacterial DNA molecule — new whole virus particles are not produced

Lytic Cycle

Virus reproduces then bursts out of host cell

Viruses

All use same genetic codem with few insignificant differences

Obligate parasites — need host cell to replicate

Simpler structure, leading to theory that they evolved before cells

Progressive Hypotheses

Viruses built up in a series of steps, taking + modifying cell components. This fits observation of some cells having virus-like components

Regressive Hypotheses

Viruses developed from cells by loss of cell components. This fits observation that both viruses and bacteria have variation of complexity, self reliance.

Influenza Virus

Caused by enveloped virus, uses RNA as genetic material, replicates using RNA replicas which do not proofread/correct errors — leading to high mutation rates

HIV

Retrovirus that uses reverse transcriptase to convert RNA genome to DNA — enzyme does not proofread/correct errors, leading to many mutations. Most mutations are harmful to the virus

Species

Group of organisms with shared traits that inbreed in the wild. (How does this definition work for organisms that produce asexually?)

Genome

Whole of genetic information of an organism, the total amount of DNA, contains genes

Organism

Individual plant, animal, bacterium, any other living thing, variety of [blank] living today is immense

Morphology

Idea of species as a group of organisms that share particular outer form, inner structure

Binomial System

International system biologists use to name species. Various rules to binomial nomenclature:
- Genus name begins with capital letter

- Species name begins with lowercase letter

- In typed/printed text, binomial is in italics

- After binomial has been used once in text it can be abbreviated to genus initial, full species name

Biological Species (concept)

Species as group of organisms that can be successfully inbred + produce fertile offspring

Population

Group of organisms of same species, living at same area at same time

Chromosome Number

Fundamental characteristic of any species, during evolution number can decrease if chromosomes fuse or increase if they split

Haploid

One set of chromosomes (gametes)

Diploid

Two sets of chromosomes (body cells)

Humans

Have 46 chromosomes (ceteris paribus)

Genes

Length of DNA carrying sequence of hundreds to thousands of bases

Alleles

Alternate form of gene, differ from each other in base sequence

SNP

Single Nucleotide Polymorphine — organisms of same species have same gene sequences with chance of variation

Whole Genome Sequencing

Determining entire base sequence of organism’s DNA

Vertical Gene Transfer

Genese transferred from parent to offspring

Horizontal Gene Transfer

Genes transferred from 1 species to another (can even be distantly related species) — most frequently seen in bacteria, less frequent among eukaryotes

Dichotomy

Division into 2

Dichotomous Key

Numbered series of pairs of descriptions — in each pair one should clearly match species, one should clearly be wrong

DNA Barcodes

Short sections of DNA from one gene — allows scientists to identify species from small pieces of tissue, otherwise difficult to recognize

Environmental DNA (eDNA)

DNA released from organism into environment (feces, skin, hair)

Classification

Involves placing organisms in groups according to their traits/evolutionary origins

Taxon

Any classification group, plural is taxa

Hierarchy of Taxa

Kingdom

Phylum

Class

Order (so on)

Family (contains 1+ genera)

Genus (contains 1+ species)

Species

Clade

Group of organisms evolved from a common (shared) ancestor. Includes all species alive today + ancestral species, every species is in multiple

Molecular Clock

Number of differences to estimate time since 2 species diverged from a common ancestor, assuming differences happen at constant rate. Important to remember assumption is made that mutations compile at constant rate

Cladogram

Branching diagram of clade, represents ancestor-descendant relationships (tree diagram with # of branches)

Evolution

Characteristics of populations changing over time, only concerns heritable characteristics — traits inherited by offspring from parents

Darwinism

Evolution by natural selection (correct theory) — Characteristics of individual organisms can change during their lifetime (children learn the language their parents speak)

Lamarckism

Evolution based on inheritance of acquired characteristics (WRONG)

Artificial Selection

Repeatedly selecting and breeding individuals most suited for humans

Breeds of species deliberately modified and bred by humans

Phenotype

Physical appearance

Analogous Structures

Had different origins but became similar because they perform same/similar functions — called convergent evolution (evolutionary explanation)

Cladistics

Increasingly used to deduce evolutionary origins of organisms, structures

Speciation

Formation of a new species by the splitting of an existing species — For this to happen 2 processes need to occur (Reproductive Isolation + Differential Selection)

Gene Pool

Genes of a population → for speciation to occur, barriers must block gene flow between 2 population [blank]

All genes and alleles present in a population

Geographical Seperation

Most obvious/common (probably) cause of reproductive isolation. Gaps in range of species → divide into separate populations. Gaps could be from physical barriers (ex. mountain ranges) which prevents interbreeding = gene pools are seperate

Natural Selection

Can cause trait changes in population, however if 2 populations have same [blank], they will keep same traits, stay same species

Differential/Divergent Selection

Where there are significant differences in natural selection — causes traits of 2 populations to become increasingly different (when taxonomists consider it significant, the populations get classified as seperate species)

Allopatric Speciation

Occurs when populations in different geographical regions become seperate species

Sympatric Speciation

Less common, population of same geographical region split into 2 populations become seperate species because they don’t interbreed

Adaptations

Characteristics that make an individual suited to its environment/way of life

Modification

Process is “adaptation”, traits developed from this process = an adaptation — structure & function is developed over time

Adaptive Radiation

Speciation and adaptation to new niches, happening repeatedly

Pattern of diversification where species that have evolved from a common ancestor occupy range of ecological roles

Minimizes competition between species, allows them to coexist → migration can occur from allopatric to sympatric

Interspecific Hybrids

Produced by cross-breeding members of different species, hybrids combine traits of bred species

Polyploid Organisms

Have more than 2 sets pf homologous chromosomes

Polyploidy

Has happened many times in evolution

Consequence of duplication of chromosomes in cell without subsequent cell division → whole genome duplication

Autotetraploid

All sets of chromosomes come from same organism

Autotetraploidy

Often associated with low fertility rates because 4 chromosome pairs and mis-pairing is very likely during meiosis

Allotetraploids

Can interbreed with other allotetraploids but not parent species

They are new species

Result of 2 step process:

1. Different species cross-breed

2. Any cell in interspecific hybrid duplicates chromosomes, but doesn’t divide

Biodiversity

Variety/Multiformity of life, exists at multiple levels (opposite of unity)

Ecosystem Diversity

Variety in combo of species living in communities, partly due to varied environments

Species Diversity

Many different species on evolutionary tree of life, have varied body plans, internal structures, etc.

Genetic Diversity

Variety in gene pool of each species, variation of populations

Overharvesting

If humans take things (resources) from natural ecosystems at a faster rate than species can reproduce, extinction will occur

Habitat Destruction

Natural habitats like forests/grasslands were destroyed for human agriculture & cities

Invasive Species

When alien species are introduced to ecosystems they can drive native species to extinction from predation, disease or competition for resources

Pollution

Vast range of substances that are released into the environment and pollute ecosystems

Global Climate Change

Plants/animals adapt to conditions, conditions that change gradually allow them to evolve BUT human activities → rapid changes