SL Bio Review

Midterm

Carbon tetravalence

Carbon can form four covalent bonds

Alpha glucose

Glucose with the –OH group on carbon 1 facing down.

Beta glucose

Glucose with the –OH group on carbon 1 facing up.

Starch

Plant energy storage polysaccharide made of α-glucose.

Cellulose

Structural polysaccharide in plant cell walls made of β-glucose.

Glycoprotein function

Cell recognition and cell signaling.

What unites lipids

They are hydrophobic and mostly insoluble in water.

Saturated fatty acids

No double bonds; solid at room temperature.

Unsaturated fatty acids

One or more double bonds; liquid at room temperature.

Phospholipid orientation

Hydrophilic heads face water

Amphipathic

Having both hydrophilic and hydrophobic regions.

Amino acid

The monomer of proteins containing an amino group

Peptide bond

Covalent bond formed between amino acids during condensation.

Condensation reaction

Forms bonds by removing water.

Primary structure

Sequence of amino acids in a polypeptide.

Secondary structure

α-helices and β-pleated sheets stabilized by hydrogen bonds.

Tertiary structure

Overall 3D shape formed by R-group interactions.

Quaternary structure

Association of two or more polypeptide chains.

Denaturation

Loss of protein shape due to heat or pH changes.

Enzyme

A biological catalyst that lowers activation energy.

Active site

Region where the substrate binds to the enzyme.

Induced fit

Enzyme changes shape slightly when substrate binds.

Competitive inhibitor

Competes with substrate for the active site.

Noncompetitive inhibitor

Binds away from the active site

Optimum temperature

Temperature at which enzyme activity is highest.

Optimum pH

pH at which an enzyme works most effectively.

Activation energy

Energy needed to start a chemical reaction.

Nucleotide

Phosphate group

Purines

Adenine and guanine.

Pyrimidines

Cytosine

DNA

Double-stranded nucleic acid that stores genetic information.

RNA

Single-stranded nucleic acid involved in protein synthesis.

Antiparallel

DNA strands run in opposite 5’→3’ directions.

Complementary base pairing

A pairs with T

Chargaff’s rule

Amount of A = T and G = C in DNA.

Helicase

Unzips DNA by breaking hydrogen bonds.

DNA polymerase

Adds nucleotides in the 5’→3’ direction.

Leading strand

Synthesized continuously toward the replication fork.

Lagging strand

Synthesized in fragments away from the fork.

Semiconservative replication

Each new DNA molecule contains one old strand.

Transcription

mRNA is made from a DNA template.

Translation

Ribosomes synthesize a polypeptide using mRNA.

Mutation

Change in DNA sequence; can be harmful

Biological species concept

Species can interbreed and produce fertile offspring.

Limitation of BSC

Cannot be applied to asexual organisms or fossils.

Human diploid number

46 chromosomes.

Chimpanzee diploid number

48 chromosomes.

Variation within species

Differences among individuals of the same species.

Variation between species

Differences between different species.

Binomial nomenclature

Two-part scientific name: genus and species.

Clade

Group of organisms with a common ancestor.

Node

Point where lineages diverge on a cladogram.

Outgroup

Species used for comparison outside the group studied.

Three domains

Bacteria

Evolution

Change in heritable traits of a population over time.

Natural selection

Individuals with advantageous traits reproduce more.

Homologous structures

Same origin

Analogous structures

Same function

Allopatric speciation

Speciation due to geographic isolation.

Sympatric speciation

Speciation without geographic isolation.

Gradualism

Slow

Punctuated equilibrium

Rapid change followed by stability.

Lamarck

Evolution occurs through acquired characteristics.

Darwin

Evolution occurs through natural selection.

Variation

Differences among individuals in a population.

Competition

Struggle for limited resources.

Fitness

Ability to survive and reproduce.

Directional selection

One extreme phenotype favored.

Stabilizing selection

Average phenotype favored.

Disruptive selection

Extreme phenotypes favored.

Cell theory

All living things are made of cells.

Structures in all cells

Cell membrane

Endosymbiotic theory

Mitochondria and chloroplasts originated from bacteria.

Evidence for endosymbiosis

Circular DNA

Compartmentalization

Separation of processes using organelles in eukaryotes.

Protein secretion pathway

Ribosome → RER → Golgi → vesicle → exocytosis.