Micro Exam 3

Metabolism

All of the chemical reactions that occur within an organism

Anabolism

Build up, require ATP, endergonic

Catabolism

Breakdown, exergonic

Metabolites

intermediates and products of metabolism

Enzymes

Proteins that speed up chemical reactions (catalysts)
Can be reused
Promote reaction by serving as physical site for specific substrate molecules to position

Do enzymes have high or low specificity

High

Simple enzymes

Just one protein

Conjugated enzymes (haloenzymes)

Apoenzyme (needs helper), cofactors or coenzymes (helpers)

Cofactors

inorganic elements, metallic cofactors are most common, activate enzymes

coenzymes

organic factors, vitamins most common

Exoenzymes

larger molecules, transported outside the cell

endoenzymes

smaller molecules, remain inside the cell

constitutive enzymes

always present, always working, always on

regulated enzymes

not constantly present, turned on or off in response to changes in substrate concentration

condensation reaction

water released, anabolic

hydrolysis reaction

catabolic, uses water to break apart peptide bonds

denaturation

weak bonds that maintain the shape of the apoenzyme are broken

competitive inhibition

substance that resembles the normal substrate competes with the substrate for the active site

allosteric inhibition

inhibition by a binding event at a site different from the active site, which induces a conformational change and reduces the affinity of the enzyme for its substrate

enzyme repression

automatic suppression of enzyme synthesis when end product buid to excess

enzyme induction

enzymes are induced when suitable substrates are present, organism can adapt and prevents waste

endergonic reactions

consume energy

exergonic reaction

produce energy

aerobic respiration

glycolysis, krebs cycle, etc

anaerobic respiration

glycolysis, krebs cycle, etc, O2 is not final electron acceptor (nitrogen)

fermentation

glycolysis, organic compounds are the final electron acceptors

glycolysis

glucose is oxidized and produces two pyruvic acids and NADH, occurs in cytoplasm

krebs cycle

one glucose yields 2 pyruvates, generates 3CO2 molecules and NADH and FADH2, occurs in mitochondria for eukaryotes and cytoplasm for prokaryotes

ETC

accepts electrons from NADH and FADH2, oxidative phosphorylation, major contributor of ATP, occurs in the mitochondria of eukaryotes and the cell membrane for prokaryotes, yields 34 ATP

fates of pyruvic acid

fermented anaerobically, oxidized completely through krebs and etc, raw material for synthesizing amino acids and carbohydrates

oxidative phosphorylation

ETC shuttles elctrons down the chain, energy is released and used by ATP synthase complexes to produce ATP

chemiosmosis

A process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme

aerobic metabolism ATP yields

38 ATP

Gluconeogenesis

formation of glucose from noncarbohydrate sources

deamination

amino acids converted into energy sources

amination

pyruvic acid can be converted into amino acids

transmination

metabolic intermediates can be converted into amino acids that are in low supply

genetics

study of heredity

genome

sum of total genetic material (DNA)

chromosome

discrete cellular structure composed of a neatly packaged DNA molecule

gene

fundamental unit of heredity, responsible for traits

structural genes

genes that code for proteins

regulatory genes

genes that control gene expression

genotype

genetic makeup

phenotype

expression of genotype, physical characteristics

DNA packaging for prokaryotes

gyrase, supercoils chromosome into a tight bundle

DNA packaging for eukaryotes

histone protein, three or more levels of coiling

nucleotide is composed of

deoxyribose sugar, phosphate group, nitrogenous base

adenine binds with

thymine (2 hydorgen bonds)

guanine binds with

cytosine (3 hydrogen bonds)

structure of DNA

antiparallel, double helix, one strand runs 5' - 3' and the other runs 3' - 5'
each strand is a template

maintenance of code during reproduction

each daughter cell is the same as the parent

semiconservative process

each daughter cell gets 1/2 genome from parent

origin of replication

Site where the replication of a DNA molecule begins.

replication fork

in DNA molecules, there are two, each has its own set of enzymes

can RNA replicate right away

no, has to be turned into DNA first (reverse transcrption)

helicase

unzips the helix

template for the leading strand

orientated 3' - 5'

DNA polymerase III

synthesizes new DNA only in the 5' to 3' direction, toward replication fork, proofread for mistakes

template for the lagging strand

orientated 5' - 3', synthesis proceeds backward, away from replication fork

primase

adds RNA primer

Okazzaki fragments

lagging strand, , new DNA

DNA polymerase I

removes rna primer, replaces gaps between okazakki fragments with correct nucleotides

ligase

An enzyme that connects two fragments of DNA to make a single fragment (nick)

transcription

dna to rna

translation

rna to protein

triplets

form dna

codons

specific for one amino acid

compare/ contrast dna and rna

rna is single stranded, C, A, U, G, ribose sugar
dna is double stranded, A, T, G, C, deoxyribose sugar
both have nucleic acids

mRNA (messenger RNA)

translated, carries master code to ribosomes, code for sequence of amino acid, message is in codons

tRNA

not translated, carries amino acids to ribosomes during translation, codes for specifying amino acids (translator)

rRNA

not translated, carries amino acids to ribosomes, codes for large structural rRNA molecules

primer

not translated, primes dna, codes for rna thar can begin dna replication

anticodon

complementary to codon in mRNA, on tRNA

initiation

rna polymers bind to promotor region upstream of the gene

promotor region

where rna polymerase lands on, at the beginning before AUG start codon

elongation

rna polymerase adds nucleotides complementary to the dna template strand 5' - 3', U replaces T

termination

rna polymerase recognizes stop codon, releases transcript

what does it mean to say the code is redundant

multiple codons code for the same amino acid

polyribosomal complex

prokaryotes, one mRNA can feed through more than one ribosome simultaneously

compare and contrast prokaryotic translation and transcription vs eukaryotic translation and transcrption

prokaryotes: transcrption and translation happen simultaneously, do not have any excess junk, use fermylmethionine, codes multiple mRNA

eukaryotes: have a lot of junk genome that needs spliced out, does not use fermylmethionine, encodes single mRNA, does not happen simultaneously

both have the same start codon AUG, use ribosomes

exons

expressed sequences, only eukaryotes

introns

must be removed and teh exons spliced together to create final mRNA, they are not transcribed, only eukaryotes

operons

a set of genes, all of which are regulated as a single unit

inducible operon

operon that is turned ON by substrate, enzymes needed to metabolize a nutrient are produced when needed

repressible operon

genes in a series that are turned OFF by the product

regulator

structural gene, codes for repressor

control locus

composed of promotor and operator (operator does not get expressed, regulatory gene)

Structural locus

made of 3 genes each coding for an enzyme needed to catabolize lactose

point mutation

addition, deletion, or substitution of a few bases, results in frameshift, always severe

inversion

switches two bases, no frameshift

missense mutation

changes codon into different codon

nonsense mutation

codes for stop codon

silent mutation

chnages codon but still codes for the same amino acid

mismatch repair enzymes

locates and repairs mismatched bases that were not repaired by dna polymerase

light repair enzymes

for UV light damage

excision repair enzymes

locates and repairs incorrect sequence by removing a segment of the dna and adds the correct nucleotides

genetic recombination

occurs when an organism acquires and expresses genes that originated in another organism

conjugation

transfer of plasmid or chromosomal fragment between two living bacterial cells of the same species via direct contact (pili) both donor and recipient become F+

high frequency recombination

donor's fertility plasmid has been integrated into the bacterial chromosome (conjugation)