Chapter 1 - The Cell

Question 1

Cytosol

Answer 1

What cell membrane is composed of.

Semi fluid cytosol - allows for diffusion of molecules throughout the cell.

Question 2

Histones

Answer 2

Organizing proteins around which linear DNA is wound.

Package and order DNA into structural units called nucleosomes (grouped I to sets of 8, called histone octamers) Histones are the chief protein component of chromatin, acting as spools around which DNA winds. Play a role in gene regulation.

Histone -> histone octamer -> nucleosome -> chromatin

Question 3

What is the cytoskeleton made up of (3)

Answer 3

1. Microfilaments (ACTIN)
2. Microtubules (TUBULIN)
3. Intermediate filaments

Question 4

What are kinesin and dynein?

Answer 4

Motor proteins which pass along microtubules in the cell cytoskeleton

Question 5

Centrioles

Answer 5

Found in centrosome.

Organizing centers for microtubules - organized in 9 triplets with a hollow centre.

During mitosis, centrioles move to opposite sides of the cell and organize the mitotic spindle.

Question 6

Chromatid

Answer 6

One copy of a newly replicated chromosome (joined to the other copy by a single centomere)

Question 7

Parenchyma

Answer 7

Functional parts of an organ

Question 8

Examples of connective tissues:

Answer 8

Bone
Cartilage
Tendons
Ligaments
Adipose tissue
Blood

**CT often produces and secretes COLLAGEN and ELASTIN.

Question 9

Archaea

Answer 9

Single-celled
Lack nucleus
Extremophiles

Start translation w methionine
Contain RNA polymerases
Associated DNA with histones

Known for using alternate sources of energy

Question 10

Mutualistic symbiotes

Answer 10

When both humans and bacteria benefit from the relationship.

(Ie not a pathogen)

Question 11

Gram positive cell wall

Answer 11

Thick peptidoglycan layer
Lipoteichoic acid (immune reaction)
No outer membrane

Stains crystal violet

Question 12

Gram negative cell wall

Answer 12

Thinner peptidoglycan layer
Phospholipid and lipopolysaccharide outer membrane
(Lipopolysaccharide = immune resp, stronger than Lipoteichoic acid)

Stains SAFRANIN (red-pink) counterstain

Question 13

Chemotaxis

Answer 13

Ability of a bacterial cell to detect chemical stimuli and move toward or away from it (via flagella)

Question 14

Plasmids

Answer 14

Small DNA molecule, separate from the chromosomal DNA, that can replicate on it’s own.

Linked with advantages such as antibiotic resistance.

Eg: sex factors are plasmids that contain the genes necessary for donor make bacteria to form the sex pili (appendage used for conjugation)

Question 15

4 basic tenets of cell theory

Answer 15

1. All living things are composed of cells
2. The cell is the basic unit of life
3. Cells arise only from preexisting cells
4. Cells carry genetic info (DNA) from parent to daughter cell

Question 16

Forms of genetic recombination (4) (ways for prokaryotes to obtain genetic information outside of binary fission)

Answer 16

1. Transformation
2. Conjugation
3. Transduction
4. Transposons

Question 17

Episome

Answer 17

A subset of plasmids that is capable of integrating into the genome of the bacterium

Question 18

Transformation (genetic recombination)

Answer 18

Integration of foreign genetic material into the host genome. Foreign material often come from lysis of other nearby bacteria.

Gram-negative rods are often able to carry out this process.

Question 19

Conjugation (genetic recombination)

Answer 19

Sexual reproduction

Forming of a conjugation bridge between a donor male (+) and donor female (-) via “sex pili”.

Question 20

Transduction (genetic recombination)

Answer 20

Only one of these processes that requires a vector (virus that carries genes from one bacteria to another).

Bacteriophages (viruses that infect bacteria) can accidentally trap a segment of DNA during assembly. When it goes to infect another bacterium, it releases this trapped DNA into the new host cell, giving it additional genes.

Question 21

Transposons (genetic recombination)

Answer 21

Genetic elements capable of inserting and removing themselves from the genome.

If a transposon is inserted within a coding region of a gene, that gene may be disrupted.

Question 22

Bacterial growth phases (4)

Answer 22

1. Lag phase
2. Exponential phase (log phase)
3. Stationary phase
4. Death phase

Question 23

Physical structure of a virus (5)

Answer 23

Genetic material (DNA or RNA, single or double stranded, linear or circular)

Protein coat (capsid)
Envelope containing lipids (sometimes)

Specific to bacteriophages: 
Tail sheath (act as a syringe)
Tail fibers (recognize and connect to host cell)

Question 24

Virions

Answer 24

Viral progeny produced by a virus once it has hijacked a cell’s machinery. Virions are released to infect other cells.

Question 25

Chromatin

Answer 25

Material of which the chromosomes of organisms other than prokaryotes (bacteria) are made of.

Consists of protein, DNA, and RNA.

Question 26

What receptors do HIV viruses bind to on white blood cells?

Answer 26

CD4 and CCR5

Question 27

What is a retrovirus

Answer 27

Enveloped
Single-stranded RNA virus
Carries enzyme called reverse transcriptase

Question 28

What happens after a cell has been infected by a virus? (This is how the virus reproduces) IE where in the cell does it go?

Answer 28

TRANSLATION of genetic material

Viral DNA must go to nucleus
Gets transcribed to mRNA
mRNA goes to cytoplasm where it is translated to proteins (by the ribosomes)

+-sense RNA viruses go directly to the cytoplasm to become proteins

–sense RNA viruses need to make a complementary RNA strand via RNA replicate, and then can be translated to make proteins.

DNA from retroviruses goes to the nucleus where it can be integrated into the host genome.

Question 29

What components are used to translate RNA into proteins?

Answer 29

Ribosomes
tRNA
Amino acids
Enzymes

Question 30

3 ways for progeny release

Answer 30

1. Initiating cell death (spilling of viral progeny)
2. Lysis (of host cell due to too large numbers of virions)
3. Extrusion (like exocytosis) - allows virus to continue using haor cell to keep reproducing

**a virus in extrusion is said to be in a PRODUCTIVE CYCLE

Question 31

What is the lytic cycle

Answer 31

The bacteriophage maximizes use of a cell to make as many virions as possible.

Bacteria in the lytic cycle are referred to as VIRULENT

Question 32

What is the lysogenic cycle

Answer 32

Once the viral DNA has entered the host cell, rather than simply replicate endlessly, it will integrate into the host genome.

It is then called a PROVIRUS or PROPHAGE.

Environmental factors can cause the provirus to leave at some point, and recent to a lytic cycle. Trapping of segments of the bacterial genome may occur (which results in TRANSDUCTION of genes from one bacteria to another)

Question 33

what is a prion and how does it cause disease

Answer 33

Prions are infectious proteins

Cause disease by triggering misfolding of other proteins.

Usually convert a protein from an alpha-helical structure to a beta-pleated sheet. Leads to reduced cell function.

Ex: Bovine spongiform encephalopathy, Creutzfeldt-Jakob disease, familial fatal insomnia.

Question 34

What is a viroid

Answer 34

A small plants pathogen
Has a very short, circular, single-stranded RNA.

Virons bind to a large number of RNA sequences and silence certain genes in plants. This prevents synthesis of some proteins and causes metabolic problems in the host cell.

Mostly know as a plant pathogen, but human examples include: hepatitis D virus (alone is innocuous, but with Hep B, silences certain genes successfully)

Question 35

What does the nucleolus do?

Answer 35

Synthesis of ribosomal RNA (rRNA)