SHSU Microbiology Exam 2

Metabolism:

•All biochemical reactions needed for life

Catabolism

Metabolic pathways that break down molecules, releasing energy. (to obtain energy)

Exergonic

Anabolism

Metabolic pathways that construct molecules, requiring energy.

Endergonic

What does the metabolism rely on?

Relies on electron donors directing electrons to electron acceptors

What does ATP stand for and what is it?

Adenosine triphosphate; high energy phosphate molecule required to provide and store energy for cellular function.

How do cells conserve energy?

by conversion into a form that can do work

Free energy

energy available to do work

What are the 4 fundamental metabolic requirements?

1. Water

2. Carbon and other nutrients

3. Free energy

4. Reducing power

Reducing power

electrons available in NADH and FADH2

1 mole of glucose could produce___ moles of ATP but actually produces ___ moles of ATP. Why?

91;38

Most is lost as heat

Redox reactions include:

oxidation-reduction (two half reactions)

Redox reaction

▪Electron donor: transfers electrons (oxidized)

▪Electron acceptor: adds electrons (reduced)

▪e.g., Aerobic respiration of glucose

Electron donor: glucose, electron acceptor: O2

Phototrophs

obtain energy from light

oxygenic photosynthesis

photosynthesis that produces oxygen

Chemotrophs

obtain energy from chemical reactions

Aerobic

requires oxygen as electron acceptor

Anaerobic

reactions use anything other than O2 as electron acceptor

Chemoorganotrophs

obtain energy and reducing power from organics

Chemolithotrophs

obtain energy and reducing power from inorganics

Heterotroph

Obtain carbon from organics

Autotrophs

Obtain carbon from CO2

primary producers

An autotroph, synthesize organic matter from inorganic matter

Catabolism depends on

electron flow from electron donor to electron acceptor

Reduction potential

the affinity of substance for electrons

substrate-level phosphorylation

energy-rich substrate bond hydrolyzed directly to drive A T P formation (e.g., hydrolysis of phosphoenolpyruvate)

oxidative phosphorylation

Movement of electrons generates proton motive force (electrochemical gradient) used to synthesize A T P

Phosphorylation

light used to form proton motive force

activation energy

the minimum amount of energy required to start a chemical reaction

catalyst

substance that speeds up the rate of a chemical reaction

Enzymes

Major cellular catalysts

Glycolysis

the breakdown of glucose by enzymes, releasing energy and pyruvic acid.

Embden-Meyerhof-Parnas pathway

another name for glycolysis

glycolysis products

2 pyruvate, 2 NADH, 2 ATP

Citric Acid Cycle

In cellular respiration, series of reactions that break down glucose and produce ATP; energizes electron carriers that pass energized electrons on to the electron transport chain.

Citric Acid Cycle products

1 pyruvate=

1 ATP

1 FADH2

2 CO2

3 NADH

Fermentation

Process by which cells release energy in the absence of oxygen

Fermentation must do two things:

1. Conserve energy

2. Redox balance

Fermentative Diversity

A property of microbes that comes from the fact that they can ferment disaccharides (e.g., lactose, sucrose) that first must be broken into individual components, as well as a number of other types of sugars if glucose is not available.

Respiration

•electrons transferred from reduced electron donors to external electron acceptors (e.g., O2)

In respiration where does reoxidation occur?

electron transport

Quinones

-hydrophobic non-protein-containing molecules that participate in electron transport

-accept electrons and protons but pass along electrons only

How are NADH Dehydrogenases and Flavoproteins arranged?

with increasingly more positive reduction potential

▪NADH dehydrogenase 1st, cytochromes last

Electron transport

in cytoplasmic membrane; A sequence of electron carrier molecules (membrane proteins) that shuttle electrons during the redox reactions that release energy used to make ATP.

ATP synthase

Uses energy from proton motive force to form ATP

Is ATP synthase reversible?

Yes

F1 component of ATP synthase

multiprotein extramembrane complex, faces cytoplasm

F0 component of ATP synthase

membrane-integrated proton-translocating multiprotein complex

ATP synthase produces

For every full rotation of F0 c ring, 3 ATP are formed by F1

____produces the highest amount of energy per molecules of glucose; most efficient.

aerobic respiration

lactic acid equation

pyruvic acid + NADH = lactic acid + NAD+

aerobic respiration equation

glucose + oxygen + 38 ADP + 38 P= carbon dioxide + water + 38 ATP

(C6H12O6 + 6 O2 > 6 CO2 + 6 H2) + energy

Gene

Functional unit of genetic information

informational macromolecules

nucleic acids and proteins

Pyrimidines

Cytosine and Thymine

Purines

Adenine and Guanine

How many hydrogen bonds are between A and T?

two

How many hydrogen bonds are between C and G?

three

Topoisomerase

inserts and removes supercoils

negative supercoiling

twisted in opposite sense relative to right-handed double helix; found in most cells

DNA gyrase

introduces supercoils into DNA

positive supercoiling

prevents DNA from melting at high temperatures

Central Dogma of Molecular Biology

DNA -> RNA -> Protein

Replication? What main enzyme?

DNA to DNA. DNA polymerase

Transcription

DNA to RNA; RNA polymerases

mRNA (messenger RNA)

encodes polypeptides

Translation

RNA to protein

tRNA (transfer RNA)

converts mRNA to amino acid sequence

rRNA (ribosomal RNA)

catalytic and structural ribosome components

Eukaryotes

-each gene transcribed individually into 1 mRNA

-replication and transcription are done in the nucleus

-RNA is exported outside of the nucleus for translation

Prokaryotes

-multiple genes are transcribed into 1 mRNA

-transcription and translation occur at the same time

chromosome

main genetic element

What does bacterial DNA chromosomes look like?

single circular chromosome

What does eukaryotic DNA chromosomes look like?

two or more linear chromosomes

What do most prokaryotic DNA chromosomes look like?

2 or more chromosomes

Viruses typically contain only ____ or ____.

RNA or DNA

Plasmids

small circular DNA molecules that replicate separately from the bacterial chromosome. Not essential but do have their benefits.

transposable elements

mobile pieces of DNA that can copy themselves into entirely new areas of the chromosomes

virulence factors

Promote evasion of host immune response

Bacteriocins

proteins produced by one bacterium that inhibits or kills another

Nucleotide

contains phosphate

Nucleoside

no phosphate group

All cells have what kind of RNA polymerase?

DNA dependent

Transcription uses ___ not ____.

promoters; primers

Transcriptional units

DNA segments transcribed into 1 RNA molecule bounded by initiation and termination sites

operons

In prokaryotic cells, a cluster of genes under control of a promoter.

stem-loop structure

A sequence of RNA containing internal GC base pairing such that a hairpin loop forms during its transcription, which serves as a mechanism to terminate continued transcription.

Splicing (RNA Splicing)

The process by which the introns are removed from RNA transcripts and the remaining exons are joined together. (eukaryotes)

Capping

the covalent attachment of a 7-methylguanosine nucleotide to the 5' end of mRNA in eukaryotes

Polyadenylation

the addition of multiple adenine nucleotides to the 3' end of a newly synthesized mRNA molecule (eukaryotes)

primary structure of protein

sequence of amino acids

secondary structure of protein

alpha helix and beta pleated sheet

tertiary structure of proteins

is the intricate 3D shape of conformation of a protein and MOST DIRECTLY DETERMINES THE WAY IT FUNCTIONS SPECIFICALLY.

quartenary structure of protein

The arrangement of different polypeptide chains (sub units) with each other

how many total codons are there?

61- coding

3- start/stop

=64 total

degenerate code

multiple codons encode a single amino acid

three steps of translation (protein synthesis)

1. Initiation

2. Elongation

3. Termination

initiation of translation

mRNA, first tRNA and ribosomal subunits assemble

elongation (translation)

codon recognition, peptide bond formation, translocation

termination of translation

occurs when a stop codon in the mRNA reaches the A site of the ribosome

DNA binding proteins

regulatory proteins that bind to DNA sequences and affect gene expression at transcriptional level