Test 3 Flashcards
1
Q
What are viruses?
A
- contain genetic information and can make proteins
- not cells(too small)
- infectious particle
2
Q
What type of cells are most likely infected by viruses?
A
-bacteria, archea, and protists
3
Q
How many kinds of viruses are there?
A
millions of viruses
4
Q
Where are viruses most abundant?
A
Oceans
5
Q
What organisms can viruses infect?
A
Plants, animals, fungi, and other viruses(rare)
6
Q
Can viruses reproduce on their own?
A
No, viruses need a host to reproduce.
7
Q
What is a virus composed of?
A
- nucleic acid(contains genetic information)
- protein covering
- capsid
8
Q
Are viruses alive?
A
No, not considered alive because they can’t reproduce or metabolize on their own.
“edge of Life”
9
Q
What kind of nucleic acid do viruses have?
A
DNA or RNA, called viral genome
10
Q
What is a membrane envelope made of?
A
phospholipids
11
Q
What is a capsid?
A
Genome coat
12
Q
What do membrane envelopes contain?
A
Polymerase enzymes
13
Q
Is genetic material in viruses single or double stranded?
Liner or circular
A
Can be either ss or ds.
Can be either linear or circular.
14
Q
How large are the genomes of viruses?
A
Very small, containing 3-200 genes
15
Q
What are viral envelopes made of?
A
Phospholipids and proteins
16
Q
Where does viral membrane come from?
A
Stolen from host cell
17
Q
Where do the proteins in a viral envelope come from?
A
From virus
18
Q
What is a glycoprotein?
A
Protein with carbohydrates attached
19
Q
How do viruses recognize host cells?
A
Viruses have proteins on their surface that recognize receptor proteins on host cells
20
Q
how did viruses come to use host cell receptors?
A
viruses evolved to use host cell receptors
21
Q
First step of virus replication in DNA?
A
virus enters host by injection, engulfing, or fusing membranes
22
Q
Second step of virus replication in DNA?
A
host cell begins to copy virus genome
- replication
- transcription and translation to make virus proteins
23
Q
Third step pf virus replication in DNA?
A
self assembly
-new virus uses host’s nucleotides, enzymes, and ribosomes to reassemble
24
Q
Fourth step of virus replication in DNA?
A
Production of hundreds to thousands of viruses
- can infect other cells
- host cells damaged, which cause symptoms
25
1st way RNA can act in protein synthesis?
RNA can act as mRNA
| -proteins can be directly synthesized
26
2nd way RNA can act in protein synthesis?
RNA can serve as a template for RNA synthesis
| -before proteins are synthesized
27
3rd way RNA can act in protein synthesis?
RNA serves as a template for DNA synthesis
| -occurs in retroviruses
28
Describe reverse transcription.
- Viral RNA used as template to make a single-strand of DNA
- Second DNAn strand made complementary to first
- Uses transcriptase enzyme
- double stranded DNA molecule made and incorporated into host cell DNA
- used as genome for new viruses
29
What kinds of hosts do viruses tend to bind with?
Most viruses are host specific or specific to host tissues
ex: measels-humans
cold virus-upper respiratory tract
30
What is meant by the term generalists?
Generalists are viruses that are not host specific.
| ex: west nile virus-mosqitoes->humans
31
Why do viruses have high evolution rates?
- small genomes
- high mutation rates
- recombination
- avoid immune defenses
32
Why do viruses have high mutation rates?
Virus and host polymerase is not accurate
| host polymerase is not able to repair viruses
33
What is virus recombination?
exchanging of genetic material with one another
| -swapping of viral and host DNA
34
Examples of virus evolution.
- Aviation-birds->primates
| - HIV->primates->humans
35
What are phages?
viruses that attack bacteria
36
What are bacterial lines of defense?
- Can evolve surface proteins to avoid recognition
| - enzymes that can recognize and cut up viruses
37
What is the CRISPR-Cas System?
system that recognizes and cuts up virus genomes in bacteria
38
Describe virus evolution.
- small genomes so fast replication
- high mutation rate due to polymerase sloppiness
- virus recombination
39
What are CRISPRS?
repeat sequences of genome
40
What is cas?
nuclease enzyme that forms a complex complementary RNA strand that binds to DNA from the phage
-causes this DNA to no longer be replicated
41
How is the CRIPR-cas system used to edit genes?
Can be targeted to cut any genome by using a complementary RNA to bind to any gene
- repair system will then add or delete
- without a template strand, the gene will become disabled
42
What is SARS-COv-2
Severe Acute Respiratory Syndrome Corona Virus 2
43
Where do coronaviruses get their name?
from the crownlike lipid envelope projections
44
What diseases have been caused by coronaviruses?
SARS, MERS, COIDS
45
Characteristics unique to SARS-COV-2?
large genomes, code for many proteins, low mutation rates(stable in hosts), evade host immune systems and stop host immune responses
46
What is the role of coronavirus' RNA?
Acts as mRNA
47
Describe a coronavirus genome.
- ss RNA(acts as mRNA)
- 5' caps and poly-A tails
- translated upon cell entry
- large genomes
48
Describe the coronavirus' genome.
13 genes- 27 proteins
| multiple proteins from the same gene
49
What is used to attach Covid to a cell receptor?
spike proteins
50
What is the host cell receptor?
ACE-2
51
How does spike protein attach to receptor?
The spike protein changes shape and leads to fusion
52
How does virus genome enter host?
Through a channel
53
Describe spike protein structure.
flexible and waves in a sweeping motion on a stalk
54
What is the ACE-2 receptor?
Angiotensin 1 converting enzyme 2
| -found in throat and lungs
55
What does ACE-2 do?
regulates cardiovascular function and other processes
56
What happens when infection occurs?
- virus is in cell-lining
- replicates and infects other cells
- cells lining airway damaged or killed
- inflammation of nerves leads to cough and sore throat
57
What is infection?
invasion of body by something that causes disease
58
What is inflammation
- Body's way of processing and fighting against things that harm it
- immune system will release chemicals that make the rest of the immune system work
59
What are the mild effects of covid?
- cough and sore throat
- when in upper respiratory system
- upper respiratory system: pharynx, larynx, nose
60
What are the severe effects covid?
- reduction of gas exchange
- pneumonia
- Acute respiratory Disease in lower respiratory
lower: trachea, bronchi, lungs
61
What does SARS-Cov-2 code for?
Many proteins: polymerase(RdRp)
- helicase
- single-stranded binding protein(SSB)
- exonuclease
62
Does Covid have a proofreading mechanism?
yes,
it has low mutation rates and large genome size
also has minor variations in SARS-COV-2
63
How does covid stop normal gene expression?
- Stops translation
- physically blocks binding sites on ribosomes so cell proteins can't be made
- hinders host immune system
64
What determines how translation occurs?
-structure of RNA determines how ribosomes move in translation
65
What are vesicles?
chambers of phospholipid bilayer
| viruses may "hide" in these vesicles
66
What kinds of vaccines are being developed to fight covid?
drugs that target spike proteins
| molecules that disrupt viral proteins by binding to them
67
Describe the mRNA vaccine.
- mRNA associates w/ ribosomes
- ribosomes make viral spike proteins
- host immune system perceives spike proteins and create antibodies
68
What are antibodies?
proteins produced by immune system that help neutralize pathogens
69
How does hand washing work kill viruses?
- soap and water help break apart lipid envelopes of virus
| - viral fragments get trapped in soap lipids and wash off in water hydrophilic and phobic parts
70
What limits the size of a cell?
Ratio of surface area to volume of cytoplasm
71
What tells you whether a cell is eukaryotic or prokaryotic?
if the cell is partitioned by internal membranes
72
what correctly identifies a main structural difference between viruses with envelopes or without them?
Only viruses with envelopes have their contents enclosed by a layer containing lipids
73
If a viral cell has a mutation that interferes with the addition of carbohydrates to proteins during processing in the Golgi apparatus, which is most likely to occur?
Viruses produced by that cell would have decreased ability to infect cells than the virus that originally infected the cell
74
Describe cellular structure or function.
Plant and animal cells both carry out cellular respiration, producing ATP
75
Disruption of nuclear pore complexes in a eukaryotic cell will most likely interfere with transport of which molecules out of nucleus
mRNA
76
What diseases would be helpful in analyzing
SARS and MERS because they are also coronaviruses
77
Which disease is most similar to COVID in origin + to humans?
Ebola, bats-> humans-> other humans
78
Ace-2 receptors are most important where?
Larynx
79
if a patient is suffering from a cytokine storm, what do you need to treat?
Congestion and inflammation in the lungs
80
Where would black spots appear on a an emulsion prepared 3 hours after pulse?
exterior of the cell
81
What path does protein in the secretory pathway take?
Rough ER, golgi apparatus, secretory vessels, plasma membrane
82
If being at room temp can inactivate HIV but not flu, what is the consequence?
the flu can be transmitted more easily
83
how do viruses replicate in human cells?
viral genome codes from specialized enzymes not found in host cells
84
Disassembly of lamina by chemical treatment would most likely result in what?
Change in shape of nucleus
85
A cell with dominance of rough ER is likely to be involved with what?
producing large quantities of proteins for secretions
86
Which event is associated with breakdown of food?
Digestion occurs in vesicle enclosed by membrane
87
What do mitochondria and chloroplasts have in common?
Contain their own DNA
88
What is host range determined by?
proteins
89
What is common in bacteria and viruses?
Genetic material from nucleic acid
90
Radioactive organelles detected by which
nucleus, mitochondria, and chloroplasts
91
How does E.coli work?
Virus infected by bacterium and bacteria cell population replaced with phages
92
Which virus shapes have capsids?
All of them
93
Genetic material of HIV has what kind of genome
Single-stranded RNA
94
When a virus invades a host cell, what does it always need to do?
- make copies of own genome-replication
| - make viral proteins using host resources
95
viral genomes can be either RNA or DNA. When viral genomes are RNA, it always acts as mRNA and is directly translated to proteins.
False. Some viruses RNA can act as mRNA and some can't.
96
What does the CRISPR Cas system do?
defends bacteria from viral infections
97
how does the cas-enzyme in system function?
cuts the DNA of infectious agent invading host cell
98
how is the CRISPR used for gene editing?
Disables and repairs defective target genes in a cell
99
Consider 2 cells with the same column but with different surface areas due to differences in shape. The cell with the largest surface area
Involved in rapid uptake of comps from the cell's environment
100
The Volume and surface area for 3 different cells are in table. Based on table, which statement, best explains which cells will be able to best eliminate metabolic waste.
Surface area increases when total volume remains constant
101
An early step involved involved in evolution of eukaryotic cells most likely involved in which event?
- A host cell engulfed a prokaryotic cell that could use oxygen to make energy and become and organelle
- A host cell engulfed a photosynthetic cell which became organelle
102
Which statement is correct regarding the role of cholesterol in animal cell membranes?
- cholesterol makes membrane less fluid at normal body temp
| - rigid shape of cholesterol causes to not pack together well
103
This is a protein in some prokaryotic cells that moves H+ ions out of cell. Which correctly characterizes proteins?
- integral membrane protein
- transmembrane protein
- transport membrane protein
104
What is cell theory?
- all life composed of cells
- all organisms made of 1 or more cells
- fundamental unit of life
- formed from cell division, all cells come from other cells
105
Which are prokaryotic?
- bacteria and archea
| - domains of life
106
Which are eukaryotic?
- eukarya
| - archea close related to eukarya than bacteria
107
how many types of cells do humans have?
- 200 cell types(minimum)
| - 37 trillion in human body
108
What is cell size?
-at minimum need to contain DNA and enough components to carry out metabolism and cell division
109
How is cell size determined?
It's dictated by surface Area to volume ratio
110
Describe the ratio of Surface area and volume.
as an object increases in size, it's volume increases more than it's surface area. Small cell has more SA than V
111
Formula for cell size.
SA/V
112
What size are most cells?
-Most cells are microscopic
113
How to increase Surface Area?
elongated or flat shape
| small projections called microvilli
114
What are biggest cells?
Egg cells-elephant bird eggs
| Nerve cells-laryngeal nerves in neck
115
What are the basic features of all cells?
- plasma membrane
- cytoplasm
- chromosomes
- ribosomes
116
plasma membrane
- general structure: phospholipid bilayer with many embedded proteins
- selective barrier around cell
- allows passage of oxygen, nutrients, and waste
117
chromosomes
-contain genetic material-DNA
118
Cytoplasm
-enter contents of cell except nucleus
119
cytosol
-jellylike substance that components of cells are suspended in
120
ribosomes
-synthesize proteins
121
Where is DNA in a eukaryotic cell?
DNA in nucleus
nucleus bounded by double membrane
nuclear envelope
122
Where in DNA in prokaryotic cell?
DNA concentrated in nucleoid
| not enclosed by membrane
123
Which cells have organelles?
eukaryotic cells have organelles
124
organelles?
subunits of cell enclosed by membrane
| allow for compartmentalation and specialization
125
What is a plasma membrane?
- phospholipid bilayer
| - can be highly folded to increase the surface area
