Microbiology Lecture Exam 2

pre-mRNA

Primary transcript of RNA before intron removal and exon connection

Mature mRNA

Final transcript of RNA, shorter than pre-mRNA

Mutation

Change in phenotype due to a change in genotype

Neutral mutation

Mutation that has no effect on phenotype

Beneficial mutation

Mutation that improves the phenotype

Harmful mutation

Mutation that negatively affects the phenotype

Mutant

Organism resulting from a mutation

Mutagen

Agent that causes mutations

Wild type

Characteristic or strain without any mutations

Mutant strain

Organism with a mutation

Negative effects

Mostly harmful effects, including antibiotic resistance

Point mutation

Substitution of a single base in the DNA sequence

Missense mutation

Mutation that changes a single amino acid in the protein

Nonsense mutation

Mutation that changes a normal codon into a stop codon

Silent mutation

Mutation that changes a base but not the amino acid

Back-mutation

Mutation where a mutated gene reverts to its original base

Frameshift mutation

Addition or deletion of a nucleotide that is not a multiple of 3

Spontaneous mutations

Mutations occurring in the absence of mutagens

Induced mutations

Mutations resulting from exposure to known mutagens

Proofreading

Process where DNA polymerase checks and corrects nucleotides during DNA replication

Mismatch repair

Process that locates and repairs mismatched nitrogen bases

Light repair

Repair mechanism for UV light damage

Excision repair

Process that locates and repairs incorrect DNA sequences by removing a segment of DNA and adding the correct nucleotides

Vertical gene transfer

Transmission of genetic information from generation to generation

Horizontal gene transfer

Transfer of genes between cells

Microbial Growth

Increases cell size and population size

Generation Time

Time it takes for one cell to divide

Exponential Growth

Each cycle increases population size by 2

Microbial Growth Curve

Lag phase, Log phase, Stationary phase, Death/decay phase

Lag Phase

No increases in number of cells

Log Phase

Exponential increase in number of cells

Stationary Phase

Plateau in number of cells, rate of cell division and death are equal

Death/Decay Phase

Decrease in number of cells

Genetics

Study of heredity

Genome

All genetic material in a cell

Chromosomes

Structure containing DNA that carries hereditary information

Mitochondria/Chloroplasts

Organelles containing genetic material

Plasmids

Small, circular DNA molecules

Gene

Segment of DNA that encodes a functional product

Genotype

All types of genes of an organism

Phenotype

The expressed traits

Bacterial Chromosomes

Single circular loop

Eukaryotic Chromosomes

Multiple linear

DNA Structure

Deoxyribonucleotide, Hydrogen bonds between complementary nitrogenous bases

Chemostat

Continuous culture system for microbial growth

Measure of Bacterial Growth

Direct total cell count, Direct viable cell count, Indirect cell count

Alternative Patterns of Cell Division

Fragmentation, Budding

Environmental Factors

Oxygen requirements, Temperature, pH, Osmotic pressure, Pressure

Antiparallel DNA Strands

Two DNA strands running in opposite directions

RNA Structure

Single-stranded molecule made of nucleotides

Ribonucleotide

Nucleotide that makes up RNA

Pairing

A=U, G=C

Types of RNA

Messenger RNA (mRNA), Ribosomal RNA (rRNA), Transfer RNA (tRNA)

DNA Replication

Occurs before mitosis, Semiconservative replication process

Origin of Replication

Site where DNA replication begins

Topoisomerase II (DNA Gyrase)

Relaxes the supercoiled chromosome

Helicase

Unwinds and separates the DNA strands

Primase

Synthesizes an RNA primer at the origin of replication

DNA Polymerase III

Adds nucleotides in the 5' to 3' direction

DNA Polymerase I

Removes RNA primers and replaces them with DNA

Ligase

Links DNA fragments along the lagging strand

Leading Strand

Formed continuously from 5' to 3' direction

Lagging Strand

Formed in short fragments from 5' to 3' direction

Protein Synthesis

DNA → RNA → Protein

Transcription

Synthesis of RNA using information stored in DNA

Translation

Synthesis of protein using information in mRNA

Initiation

Ribosome binds mRNA at start codon

Elongation

Polypeptide chain elongates by adding amino acids

Termination

Stop codon encountered, polypeptide is released and ribosome dissociates

The electron transport chain is part of the ____ _____ step in cellular respiration.

Oxidative Phosphorylation

In eukaryotes, acetyl-CoA synthesis takes place in the ___ ____.

Mitochondrial matrix.

During the Citric Acid Cycle, ATP is synthesized by ___ ___ ___.

Substrate level phosphorylation

The final electron acceptor in the transport chain is _____.

OXYGEN.

Fermentation occurs in:

Some aerobic organisms such as yeast, even in the presence of oxygen.

Glycogen is found in ____ and posses a large, central protein.

ANIMALS

Starch is found in___ and lacks a central protein.

STARCH

NADH is formed during what phase of glycolysis?

During phase 3.

A single molecule of glucose requires ___ "turns" through the citric acid cycle for its chemical energy to be completely harvested.

2

Where are the proteins of the electron transport chain embedded?

In the inner mitochondrial membrane.

The remaining chemical energy from the glucose is found primarily in ____ & ____.

Lactic acid and ethanol

Beta- oxidation of fatty acids DOES NOT produce what?

ATP

In cellular respiration, oxygen gains electrons. This means it is ____.

Reduced

Since oxygen is reduced, this makes is a ____ agent.

Oxidizing

Energetic coupling is made possibly by ____ synthase.

ATP

What does the anaerobic electron transport chain do?

Establishes a proton gradient between cytoplasm and extracellular fluid.

ATP is stored in ____

muscle

Glycogen is stored in ____ and then in ____.

muscle, liver, fatty acids

Chemical bonds of carbohydrates and lipids have high potential energy because their electrons are ___ from the nucleus.

AWAY.

At the end of glycolysis, carbon molecules are in the form of ____ ____.

Pyruvate molecules.

ATP is NOT generated directly in the Citric Acid Cycle. First, an intermediate is generated. This is ___.

GTP.

The first phase of glycolysis requires the input of two ATP molecules. This makes it ______.

ENDERGONIC.

In cellular respiration, glucose is ____ to CO2.

OXIDIZED

In cellular respiration, oxygen is ____ to H2O.

REDUCED

What happens in the second phase of glycolysis?

Clears out a phosphorylated sugar molecule and rearranges the products.

Glycolysis is ____ among species.

CONSERVED

TCA Cycle (Citric Acid Cycle) can run backwards for the ____ of pre-cursors to many molecules.

Production

What regulates acidity in prokaryotic organisms.

ETP.

Anaerobic respiration most likely pre-dates ____ respiration.

aerobic.

Oxaloacetate is the starting and ending molecule in the ___ ___ ___.

Citric Acid Cycle.

The Citric Acid Cycle is also known as ___ & ____.

TCA cycle and Krebs cycle.