Midterm

Question 1

What are the key characteristics of a eukaryotic cell

Answer 1

Cytoplasm, cell membrane, mitochondria, nucleus, DNA, ER, Lysosome, ribosome, golgi apparatus

Question 2

Features of a prokaryotic bacteria

Answer 2

Capsule, plasma membrane, pilli, plasma membrane, cytoplasmic INCLUSION, plasmid, ribosomes, cytoplasm, basial body, 70s ribosomes

Question 3

Difference between a gram negative and gram positive cell wall

Answer 3

Gram positive: Purple- Lipid bilayer plasma membrane and cell wall w lipotechoic acids anchoring membrane (20-80 nm, peptidoglycan is digested by lysozyme)
Gram negative: lipid bilayer plasma membrane with lipid A in it. 3 layers and 1 compartment (periplasm)

Question 4

Average size of a bacteria

Answer 4

average human cell= 25x10-6
average bacteria: 10^-6
average virus: 10^-8

Question 5

Flagella structure and function

Answer 5

-Long helical protein filaments
-Allow movement through the environment
-Different between sperm cells and bacteria

Question 6

Pilli/fimbrae structure and function

Answer 6

-Pili are used for attachment
-Attach bacteria to host cell
-E.coli use pili to attach to bladder for UTIs
-Can use gene recombination to avoid human immune system

Question 7

Capsules structure and function

Answer 7

-Polysaccharides that form a silmy surface. Protect bacteria from phagocytosis. Increase virultance. Slimeiness evades immune system and desiccation

Question 8

Cocci vs bacilli

Answer 8

Cocci= spheres, strep is chain and staph is clusters
Bacilli= rods

Question 9

Which bacteria form endospores commonly

Answer 9

clostridum and bacillus (form to evade heat and chemicals). Multilayer coat around cell when they can’t grow in environment, help remain dormant.

Question 10

Anaerobic vs aerobic final ATP

Answer 10

Anaerobic- O2 is final electron acceptor, 34 ATP are made.
Aerobic- use oxygen, 38 ATP made.

Question 11

Obligate vs facultative vs aerobe vs anaerobe

Answer 11

Obligate = absolutely needs o2
Facultative = optional
Aerobe = O2
Anaerobe = no O2 (O2 is toxic)

Question 12

Replication phases

Answer 12

Lag Phase/adjustment period = no cell division
Logarithmic Phase w/ abundant nutrients = rapid growth
Stationary Phase w/out nutrients = slow/no cell division
Death Phase w/ toxic waste accumulated = cells die

Question 12

What is gene expression

Answer 12

transcribe a gene into RNA using RNA directly or translating RNA into a protein

Question 13

What are operons

Answer 13

clusters of genes that are transcribed and translated together (form a pilli or toxin)

Question 14

What is quorum sensing

Answer 14

gene transcription is activated in response to the concentration of bacteria (when a concentration gets high enough, starts to have an impact on the host)

Question 15

Where does translation start

Answer 15

initiation complex

Question 16

Where does translation end

Answer 16

stop codon

Question 17

Ribosomes in prokaryotes vs eukaryotes

Answer 17

prokaryotes= 70s
eukaryotes=80s

Question 18

Which antibiotics target bacterial ribosomes

Answer 18

Erythromycin and aminoglycosides, tetracyclines (TEA)

Question 19

Which bacteria uses quorum sensing to be toxic

Answer 19

pseudomonas aerginosa
- Infects CF patients, activate biofilm production that hides bacteria from immune system and antibiotics

Question 20

Describe transformation

Answer 20

donor cell lysis→ DNA fragments released→ DNA integrates into the recipient DNA

Question 21

Describe transduction

Answer 21

(Generalized) donor cell infected with bacteriophage→ cell lysis and virus released→ virus infects new cell.
(Specialized) The lysogenic cell has prophage on chromosome→ inexact prophage induction → cell lysis→ virus infects a new cell and DNA incorporated into the recipient chromosome

Question 22

Descrine conjugation

Answer 22

Conjugation: Plasmid transfer→ plasmids cross the cytoplasmic bridge and enter the recipient through sex pilus. Chromosomal transfer→ Plasmid can cause the transfer of DNA which integrates with the recipient’s DNA

Question 23

Which type of gene transfer is most clinically important and doesn’t require recombination

Answer 23

conjugation

Question 24

What are most antibiotic resistances in bacteria due to

Answer 24

plasmids (resistant plasmids, plasmids via horizontal gene transfer and conjugation, recombination)

Question 25

Size range for viruses

Answer 25

Double digit nm
Small: Poliovirus (~30 nm)
Large: Poxvirus (~200-300 nm)

Question 26

Basic structure in all viruses

Answer 26

Capsid, nucleic acid

Question 27

Non-enveloped virus steps life cycle

Answer 27

Attachment: Virus binds to specific receptors on the host cell surface.
Entry: Nonenveloped viruses enter the cell by endocytosis.
Uncoating: The capsid breaks down, releasing viral nucleic acid into the host cell.
Replication: The viral genome is replicated using the host cell’s machinery.
Assembly: New viral particles are assembled inside the host cell.
Release: The virus is released from the cell via cell lysis, breaking the host cell open.

Question 28

Enveloped virus steps

Answer 28

Attachment: Virus binds to host cell receptors via spikes on the envelope.
Entry: The virus enters the cell by fusion of its envelope with the host cell membrane or by endocytosis.
Uncoating: The viral capsid disassembles, releasing the genome into the host cell.
Replication: Viral genome replication occurs using the host’s machinery.
Assembly: New viral particles are assembled, incorporating the viral genome.
Release: The virus is released by budding/exocytosis, where it acquires its envelope from the host cell’s membrane.

Question 29

What is the latest point in a virus where a CT cell can destroy a host cell without releasing virons

Answer 29

before viral assembly and release.

Question 30

What usually determines the host specificity of a virus

Answer 30

The ability for the virus to attach to the host cell

Question 31

What is the function of reverse transcriptase in retroviruses

Answer 31

Reverse transcriptase in retroviruses converts the viral RNA genome into DNA. This DNA is then integrated into the host cell’s genome, allowing the virus to hijack the host’s cellular machinery to replicate and produce more viral particles. It is a key enzyme that allows retroviruses, like HIV, to insert their genetic material into the host’s DNA.

Question 32

What are the 3 general outcomes of a viral infection

Answer 32

Lytic Infection: The virus replicates and causes the host cell to burst (lysis), releasing new viral particles. (e.g., influenza)
Latent Infection: The virus remains dormant inside the host cell and can reactivate later (e.g., herpesviruses).
Chronic Infection: The virus continues to replicate at low levels, without destroying the host cell (e.g., hepatitis B).

Question 33

What do all herpesviruses have

Answer 33

an envelope (establish latent infections)

Question 34

HSV1 viruses cause

Answer 34

cold sores

Question 35

HSV2 causes

Answer 35

genital herpes

Question 36

Varicella-zoster (HSV3)virus causes

Answer 36

chickenpox and shingles

Question 37

HSV 4 (Epstein-Barr virus) causes

Answer 37

mononucleosis (MS)

Question 38

HSV 5 Cytomeglavoris causes

Answer 38

hepatitis, pnumonitis, most common cause of birth defects

Question 39

HHV 6 and 7 causes

Answer 39

roseola in infants

Question 40

HHV 8

Answer 40

Kaposki’s sarcoma herpes (HIV)