Microbio Unit 2 Exam

what is the structure of DNA?

Double helix composed of nitrogenous bases (A,T,C,G) and a sugar-phosphate backbone

what is the structure of RNA?

a single strand composed of nitrogenic bases (A,U,C,G)

what is the genetic material of bacteria?

DNA

what is the genetic material of archaea?

DNA

what is the genetic material of fungi?

DNA

what is the genetic material of viruses?

RNA or DNA; can be double-stranded RNA, single-stranded RNA, Single-stranded DNA, or double-stranded DNA

what are the 3 processes of DNA replication?

1. initiation

2. elongation

3. termination

what happens during the first step of DNA replication?

initiation; helicase unzips the DNA strands (by breaking down hydrogen bonds). forms 2 different strands (leading and lagging strands) and makes the replication fork.

What happens during the second step of DNA replication?

elongation; DNA polymerase adds DNA nucleotides to the 3′ end of the newly synthesized template strand

What happens during the third step of DNA Replication?

In the third step of DNA replication, DNA ligase seals the gaps between DNA fragments on the lagging strand. These Okazaki fragments are joined to make one continuous strand. This finishes the new DNA molecule.

What enzymes are involved with each step of DNA replication?

inititiation- helicase

elongation- DNA polymerase and primase

termination- ligase (sometimes topoisomerase for relieving DNA twisting).

what is the structure of a codon?

three nucleotides

What 3 codons represent STOP?

1. UGA

2. UAA

3. UAG

which codon represents START?

AUG (to remember- school starts in august)

what base pair bonds with A (in DNA)

T

what base pair bonds with T (in DNA)

A

what base pair bonds with G (in DNA)

C

what base pair bonds with C (in DNA)

G

what base pair bonds with A (in RNA)

U

what base pair bonds with U (in RNA)

A

what base pair bonds with C (in RNA)

G

what base pair bonds with G (in RNA)

C

What types of RNAs are involved in Transcription?

dna → mRNA

What types of RNAs are involved in translation?

ribosome reads mRNA and tRNA transfers it to the right amino acid

what is the structure of the ribosome?

it is an organelle made up of rRNA and proteins. It has 2 parts: a large subunit and small subunit

what is a genome?

a complete set of genetic information

whats more stable: DNA or RNA?

DNA

what is considered a “fairly large polypeptide”?

a protein

what are the 2 steps of gene expression?

transcription and translation

what are the 2 tasks a cell must accomplish to multiply?

1. DNA replication

2. Gene Expression

is replication conservative, semi-conservative or nonconservative?

semi-conservative

what is DNA polymerase responsible for?

building new templates of DNA

what is primase (primers) responsible for?

telling DNA polymerase where to start

what is ligase responsible for?

forms covalent bonds between 2 nucleotides

which end can DNA polymerase add nucleotides to?

the 3’ end

what seals okazaki fragments?

DNA ligase

do bacteria perform mitosis?

no; binary fission

what is also known as the “positive strand”?

the non-template strand

why can DNA initiate without primer?

bc RNA is less stable

what are removed: introns or extrons?

introns

what remain: introns or extrons?

extrons

how many codons are there total?

64

what are the 2 different “branches” of mutations?

spontaneous mutations and induced mutations

what are the different types of mutations?

1. point mutations (changes 1 base pair)

2. frameshift mutations (removal or addition of base)

what are the subtypes of mutations within point mutations?

1. missense mutations

2. silent mutations

3. nonsense mutations

what are the subtypes of mutations within frameshift mutations?

1. insertion (adding extra bases)

2. deletion (removing base/s)

These shift the reading frame, which changes every amino acid after it.

what are silent mutations?

DNA is mutated but amino acid does not change

what are missense mutations?

the DNA is mutated and the amino acid is changed (but may not change anything in the end)

what are nonsense mutations?

causes a stop codon in the wrong place in the protein

what are the different types of horizontal gene transfer?

transformation, transduction and conjugation

what is the difference between horizontal versus vertical gene transfer?

vertical gene transfer: parent cell → offspring

horizontal gene transfer: genes from environment or neighbors → offspring

what are the different types of viruses?

1. DNA viruses (can be single stranded or double stranded. e.g. dsDNA is herpesvirus)

2. RNA viruses (ssRNA or dsRNA. e.g. ssRNA influenza virus)

3. retroviruses (use reverse transcriptase to turn RNA into DNA. e.g. HIV).

what is the “dogma of molecular biology”?

genetic information flows only in one direction, from DNA → RNA → protein; or RNA directly → protein.

what is the function of reverse transcriptase?

making a strandDNA from an RNA template

who is the discoverer of reverse transcriptase?

Howard M. Temin and David Baltimore

What is the function of PCR?

PCR is used to amplify a specific segment of DNA, making millions of copies quickly.

What is the function of gel electrophoresis?

It separates DNA, RNA, or proteins based on size and charge, allowing scientists to visualize and compare fragments.

What is the function of blotting techniques?

• Southern blot detects specific DNA sequences.

• Northern blot detects specific RNA sequences.

• Western blot detects specific proteins using antibodies.

What is the function of CRISPR-Cas9?

CRISPR-Cas9 is a gene-editing tool that can cut and modify DNA at specific locations.

What is the function of DNA cloning?

used to make identical copies of a DNA segment by inserting it into a plasmid and growing it in bacteria.

How are prokaryotes identified through chemical tests?

using biochemical tests that detect metabolic activities. For example, the catalase test checks if bacteria produce the enzyme catalase. Many tests use pH indicators and are organized in a dichotomous key.

what is phylogeny

the evolutionary history and relationships between groups of organisms

How is phylogeny between prokaryotes determined?

16S rRNA sequence analysis, DNA hybridization, and DNA base ratios (like G+C content).

What basic information should you know about coronaviruses?

are enveloped, single-stranded (+) RNA viruses from the Coronaviridae family. They have spike proteins that look like a crown. their receptor is ACE-2

How do you culture viruses and what happens on a petri plate?

Viruses are grown in living host cells, like bacteria. When viruses lyse bacteria in a soft agar layer, they form clear zones called plaques on the bacterial lawn.

What is the structure of a fungal cell wall and plasma membrane?

The cell wall contains chitin and glucan, and the membrane contains ergosterol instead of cholesterol (like in humans).

What are the groups of fungi and their features?

• Ascomycota: Sac fungi; make ascospores, includes yeasts, molds, truffles.

• Basidiomycota: Club fungi; make basidiospores, include mushrooms, rusts, and smuts.

• Mucromycota: Produce zygospores; includes Rhizopus (bread mold).

What are the groups of protozoa and their features?

• Amoebae: form and move with pseudopods; form cysts.

• Apicomplexans: Use apical complex to enter host; cause diseases like malaria.

• Dinoflagellates: single celled Marine organisms; sometimes photosynthetic, may make toxins like brevetoxin.

What are helminths?

Helminths are parasitic worms. Two main types are:

• Roundworms (nematodes)

• Flatworms (platyhelminths

what are the different types of flatworms

• Tapeworms (cestodes)

• Flukes (trematodes)

What is elephantiasis and what causes it?

caused by roundworms that block lymph vessels, leading to swelling in the limbs. The worms come from the Filarioidea family.

What are oomycetes?

not true fungi. They are protists that lack chloroplasts and are not photosynthetic. DNA shows they are closer to brown algae and diatoms.

what are the different types of algae?

• diatoms

• brown algae

• red algae

• green algae

What is green algae?

Algae closely related to plants; contain chlorophyll a and b. Some are single-celled, others form colonies like Volvox.

What are red algae?

Can be single or multicellular; contain red pigments like phycoerythrin. Nori, used in sushi, is red algae.

What are brown algae?

Large, multicellular algae like kelp; grow in cold oceans and contain the pigment fucoxanthin.

What are diatoms?

Single-celled algae with silica shells called frustules; common in water and used in diatomaceous earth.

What’s the difference between lytic and lysogenic viruses?

• Lytic viruses immediately destroy the host cell to release new viruses.

• Lysogenic viruses insert their DNA into the host’s DNA and can stay dormant, later entering the lytic cycle.

What is binomial nomenclature?

the scientific naming system that uses two names: the genus and the species (e.g., Escherichia coli).

What important viral disease has been eradicated globally?

Smallpox is the only viral disease that has been eradicated worldwide through vaccination.

what do topelasiametases do?

relieve tension in growing double helix

true or false:

most mutations are harmless

false

what is the opposite of a mutant?

a wild type

what is the human genome project?

The Human Genome Project was a big science project that mapped all the DNA bases in human cells.

what is transformation of horizontal gene transfer?

DNA taken from the environment

what is transduction of horizontal gene transfer?

DNA moved by a virus

what is conjugation of horizontal gene transfer?

DNA shared through direct contact

What’s the difference between viruses and bacteria?

Viruses can’t live on their own—they need a host. Bacteria are living cells that can survive and grow on their own.

What are the two main types of viral infections?

• Acute: Fast and short

• Persistent: Long-lasting (chronic or latent)

what kind of microscope do you need to see a virus?

Electron light microscope

what are the three shapes of viruses?

helical, complex, icosahedral

what are the different routes of transmission of viruses?

enteric (fecal-oral route)

respiratory

zoonotic (animal to human)

arboviruses (spread from insects)

sexually transmitted

What are the five steps of bacterial infection?

1. attachment

2. Genome entry

3. Synthesis

4. Assembly

5. release

what is the vectors of malaria?

mosquitoes

what weapon is found in membrane of the animal cell?

call Astra

what is a visible mass of hyphae in molds called?

mycelium