Biology/Biochemistry MCAT

binary fission

How do mitochondria replicate?

autophagy

the process of intracellular cytoplasmic debris being packaged and fused with a lysosome for degradation

microfilaments

the smallest of the three cytoskeletal components; composed of two intertwined stands and actin polymers

microtubules

the largest of the three cytoskeletal components that maintain the structure of the cell and act as highways along which motor proteins can traffic intracellular vesicles

kinesin

a motor protein that moves in an anterograde fashion from the middle of the cell to the edge

dynein

a motor protein that movies in a retrograde fashion toward the center of the cell from the edge

Intermediate filaments

the medium size component of the cytoskeletal system that provides structural support to the cell and involved in cell-to-cell adhesion processes

hydrophobic interactions

the force by which nitrogenous bases stack on top of each other in RNA and DNA

heterogenous nuclear RNA

the precursor to mRNA that must be spliced and modified

small interfering RNA

inhibit the expression of certain genes by inducing mRNA cleavage and degradation.

microRNA

inhibit the expression of certain genes by translational repression (blocking protein synthesis).

UAG, UGG, and UGA

what are the three stop codons?

DNA polymerase I

the DNA polymerase that removes RNA primer and replaces primer with DNA, and repairs DNA in both directions

DNA Polymerase II

the DNA polymerase that only repairs DNA

DNA Polymerase III

the DNA polymerase that synthesizes new DNA and proofreads DNA via 3’ to 5’ exonuclease activity

peptidases/proteases

lower the activation energy of hydrolysis making it easier to break peptide bonds

backbone hydrogen interactions

which interactions are the foundation for secondary protein structure

detergents

destabilize the hydrophobic interactions in tertiary structure

reducing agents

agents capable of breaking covalent interactions that stabilize tertiary structure

G0 Phase

the phase of the cell cycle in which the cell is not actively dividing or preparing to divide

G1 phase

the phase of interphase in which the cell grows and the cell synthesizes the protein it needs to survive.

It is at this point that the cell commits to cell division if its DNA is damage0free and conditions are right

S phase

the phase in which DNA replication occurs: 46 chromosomes replication into 92 sister chromatids

G2 phase

the phase in which the cell undergoes more growth and it must pass the final checkpoint before proceeding to mitosis

Cyclin dependent Kinases

molecules that respond to cyclins and phosphorylate and activate target proteins which promote activity of the next phase of the cell cycle

Prophase I

In which phase of meiosis does genetic recombination and crossing over occur?

Indirect fitness

This is the component of inclusive ftiness that involves relatives. It refers to the reproductive success of genetic relatives that is made possible by your support.

stabilizing selection

selects against extreme phenotypes favoring an intermediate phenotype

directional selection

one extreme phenotype is favored over another

disruptive selection

extreme phenotypes are selection over intermediate phenotypes

gene flow

the movement of alleles from one population to another due to migration between populations

genetic drift

change in the gene pool due to random chance particularly in smaller populations

parallel evolution

the development of a similar trait in distinct, but not closely related species that share a similar ancestral trait

Coevolution

occurs when two or more different species reciprocally affect each others evolution through the process of natural selection and their ecological interactions over time

Ex. host-parasites

divergent evolution

the accumulation of differences between two or more closely related populations or species, leading to speciation and homologous structures

homologous structures

similarities between the resulting species are due to their shared common ancestry

convergent evolution

the independent evolution of similar features in species of different taxonomic groups that are not closely related, creating analogous structures

analogous structures

biological features in different species that serve the same function but do not share a common evolutionary origin

n = iMRT

where n is the osmotic pressire

i = Van Hoff’s constant

R = ideal gas constant (8.314)

M = total concentration of solutes

What is Van Hoff’s Law Equation?

PV = nRT

Ideal Gas Law

flagellin

what is prokaryotic flagella made of?

microtubules

what is eukaryotic flagella made of?

transformation

bacterial absorption of genetic material from the environment. DNA in the form of plasmids can be introduced by the environment and be transcribes and translated like other DNA

Transduction

horizontal gene transfer mediated by bacteriophages

Conjugation

the swapping of genetic information between two existing prokaryotes via the fertility factor

mutagens

encompass any chemical, physical, or biological agents that change DNA sequences

carcinogens

cause or promote the development of cancer; may either work through mutagenic mechanisms or indirect mechanisms promoting prolonged inflammation

depurination

when a purine nucelotide spontaneously loses it base through hydrolysis, leaving an empty slot

deamination

when DNA bases lose an amine functional group

ex. cytosine transforms into uracil

Inborn Errors of Metabolism

genetically inherited disorders that disrupt our metabolism resulting in the accumulation or deficit of certain molecules

loss-of-function mutation

DNA mutation causing a reduction or complete loss of protein product, often occurring due to genetic changes such as nonsense mutations, frameshift mutations, or deletions that prevent the protein from being produced or function correctly

Gain-of-function mutations

results in increased protein activity or new protein function or the expression or the protein in an inappropriate location or time

Structural abnormalities

alterations in the chromosome itself and typically result in the breakage and incorrect rejoining on chromosomal segments

balanced structural abnormalities

change to a chromosome without a net loss of gain or general material

inversion

segment of chromosome detaches, rotates 180˚ and reattached to the same chromosome

pericentric inversion

inversions that include the centromere

paracentric inversion

inversions that do not include the centromere

translocation

a portion of a chromosome breaks and reattaches to a different location. Reciprocal ones tend to be harmless

unbalanced structural abnormalities

loss, gain or translocation or genetic material:

deletions, duplications, or insertions

chromosome insertion

DNA from one chromosome is deleted and added to another chromosome

Turner Syndrom

a monosomy disorder in which a female only has one X chromosome instead of a the usual two

Exonuclease

remove nucleotides from the ends of DNA strands, used by DNA polymerases because these enzymes are always at the end of the strand being replicated

Endonucleases

cleave internal phosphodiester bonds

mismatch repair

repair mechanism occurring immediately after DNA replication and continues through the G2 stage of the cell cycle

Recognizes the newly formed strand based on the lack of DNA methylation

Base excision repair

a single strand repair mechanism that can remove a single erroneous base; limited to fixing small-scale errors. Uses DNA glycosylase to "scout" and remove a specific type of damaged or incorrect nitrogenous base from the DNA backbone.

Nucleotide Excision Repair

used instead of base excision repair if larger mutation occurs involving multiple bases; use specifically to repair damage due to UV light

solvation layer

a structured, organized layer of solvent molecules—most commonly water in biological systems—that surrounds a solute particle (like an ion, polar molecule, or protein) and participates in protein folding

detergents

amphipathic molecules that break apart hydrophobic interactions by essentially "coating" the hydrophobic parts of the protein, making them soluble in water. These also disrupt charges, breaking ionic bonds too

denaturants

typically small, highly polar molecules that are used in high concentrations to completely unfold a protein's secondary, tertiary, and quaternary structures by disrupting hydrogen bonds, van der waal’s, and ionic bonds that stabilize the shape

reducing agents

protonate the cytosine residues of amino acids, breaking disulfide linkages

spatial summation

occurs when multiple presynaptic neurons release neurotransmitters together to fire an action potential

temporal summation

Temporal summation occurs when a single presynaptic neuron fires multiple times in rapid succession at the same location

glutamate

an excitatory neurotransmitter that also just shares the structure with glutamic acid - the polar, charged amino acid

salivary amylase

enzyme that breaks does starch into smaller oligosaccharides and disaccharides

Lingual Lipase

begins the process of digesting lipids

parietal cells

secrete HCL and intrinsic factor

chief cells

secrete pepsinogen which is cleaved in acidic conditions tp create pepsin, which breaks down proteins into smaller peptides which will be easier to absorb

secretin

stimulates the secretion of bicarbonate to neutralize the acidic chyme in order to maintain the more basic pH of 6-7

Cholecystokinin

stimulates the release of digestive enzymes from the pancreas and bile from the gallbladder

gastrin

a hormone released by the S cells in the duodenum that signals to the pancreas to secrete bicarbonate into the small intestine to maintain a more alkaline pH

somatostatin

a hormone that halts all pro-digestion hormones, stalls stomach emptying, and the release of pancreatic hormones

brush border disaccharideases

enzymes secreted by enterocytes of the small intestine that digest disaccharides into monosaccharides at the brush border

sucrase

digests sucrose into glucose and fructose

maltase

digests maltose into two glucose

Lactase

digests lactose into glucose and galactose

vitamins C and B

water soluble vitamins

Vitamins A, D, E, and K

lipid soluble vitamins

TATA box

a recognition sequences of RNA polymerase during transcription

introns

non-coding segments that are excised during mRNA splicing

Shine-Dalgarno sequence

the specific recognition sequence in prokaryotic mRNA for translation

ubiquitination

the addition of ubiquitin protein which can be used to designate certain proteins for degradation in the cell

positive induction

an activator protein is normally inactive, meaning the operon is off. When the inducer binds to the activator, the operon turns on

positive repression

activator protein is normally active. A repressor binds to the activator, turning the operon off

negative induction

at default, the operon is off. An inducer binds to the repressor activating the operon

negative repression

at default the operon is on and the repressor is inactive. A corepressor binds to the repressor, activating it, turning off the operon

methylation

the addition of methyl groups to cytosine or adenine nucleotides to deactivate, or silence, gene sequences, preventing their expression

de novo mutations

mutations that arise spontaneously at an error rate of 1/100,000 bp, but thankfully, 99% of those are corrected —> 1/10,000,000 bp error rate

mutagens

encompass any chemical, physical, or biological agents that change DNA sequence

carcinogens

cause or promote development of cancer; may work either through mutagenic mechanisms or indirect mechanisms promoting prolonged inflammation

depurination

when a purine nucleotide spontaneously loses its base, through hydrolysis

deanimation

when DNA bases lose an amine functional group (cytosine transforms into uracil)