Biology

Question 1

Four basic tenets of cell theory:

Answer 1

-all living things are composed of cells
-the cell is the basic functional unit of life
-cells arise only from preexisting cells
-cells carry genetic information in the form of DNA which can be passed on from parent to daughter cell

Question 2

Are viruses living organisms? (3 reasons)

Answer 2

No, because they are acellular, cannot reproduce without the assistance of a host cell, and may use RNA as their genetic material

Question 3

Characteristics of a eukaryotic cell:

Answer 3

contain membrane bound organelles, a nucleus, and may form multicellular organisms

Question 4

What makes up the cell membrane?

Answer 4

phospholipids, which organize to form the hydrophilic interior and exterior surfaces with a hydrophobic core

Question 5

Purpose of the cytosol:

Answer 5

suspend organelles and allow diffusion of molecules throughout the cell

Question 6

Nucleus:

Answer 6

-contains DNA organized into chromosomes, surrounded by nuclear membrane/envelope and a double membrane with nuclear pores for two-way exchange of materials between the nucleus and the cytosol.

Question 7

DNA is organized into coding regions called ——

Answer 7

genes

Question 8

Nucleolus:

Answer 8

subsection of the nucleus in which ribosomal RNA (rRNA) is synthesized

Question 9

Mitochondria:

Answer 9

-outer (forms barrier with the cytosol) and inner (folded into crystal and contains enzymes for the ETC) membrane. Between membranes is the intermembrane space and matrix
-can divide independently of the nucleus via binary fission and can trigger apoptosis

Question 10

Lysosomes:

Answer 10

contain hydrolytic enzymes that can break down substances ingested by endocytosis and cellular waste products.

Question 11

Endoplasmic reticulum:
Smooth and Rough

Answer 11

-series of interconnected membranes
Smooth: lipid synthesis and detoxification
Rough: studded with ribosomes, which permit translation of proteins destined for secretion

Question 12

Golgi apparatus:

Answer 12

consists of stacked membrane-bound sacs in which cellular products can be modified, packaged, and directed to specific cellular locations

Question 13

Peroxisomes:

Answer 13

contain hydrogen peroxide and can break down very long chain fatty acids via B-oxidation
-also in phospholipid synthesis and pentose phosphate pathway

Question 14

What does the cytoskeleton do?

Answer 14

provides stability and rigidity to the overall structure of the cell, while also providing transport pathways for the molecules within the cell

Question 15

Microfilaments:

Answer 15

composed of actin-
structural protection for cell and cause muscle contraction
help cleavage furrow during cytokinesis in mitosis

Question 16

Microtubules:

Answer 16

composed of tubulin
create pathways for motor proteins like kinesis and dyne to carry vesicles
also contribute to structure of cilia and flagella
-centrioles are found in centrosomes and are involved in microtubule organization in the mitotic spindle

Question 17

Intermediate filaments:

Answer 17

cell-cell adhesion and maintenance of the integrity of the cytoskeleton; help anchor organelles
ex. keratin

Question 18

Epithelial tissues:
-Simple
-Stratified
-pseudo-stratified

Cell shapes

Answer 18

cover the body and line its cavities, protecting against pathogen invasion and dessiccation
-epithelial cells form the parenchyma (functional parts of the organ)
-may be polarized

-1layer
-many layers
-appear to have multiple layers, actually only 1

-cuboidal -cube
-columnar - long +narrow
-squamous -flat

Question 19

Connective tissues:

Answer 19

support the body and provide framework for epithelial cells
-form the storm (support structure) by secreting materials to form an extracellular matrix
-bone, cartilage, tendons, etc

Question 20

Prokaryotes:

Answer 20

do not contain membrane-bound organelles; contain their genetic material in a single circular molecule of DNA located in the nucleiod region

Question 21

3 domains of life

Answer 21

archaea: extremophiles
bacteria
eukarya: non-prokaryotic domain

Question 22

Bacteria can be classified by shape:

Answer 22

cocci: spherical
bacilli: rod-shaped
spirilli: sprial-shaped

Question 23

Bacteria classification based on metabolic processes:

-obligate aerobes
-Obligate anaerobes
-facultative anaerobes
-aerotolerant anaerobes

Answer 23

-require oxygen for metabolism
-cannot survive in oxygen containing environment and only carry out anaerobic metabolism
-can survive with out without oxygen and toggle between metabolic processes
-cannot use oxygen for metabolism, but can survive in oxygen containing environment

Question 24

the cell wall and cell membrane from the —— which does: in bacteria

Answer 24

envelope, controls the movement of solutes into and out of the cell

Question 25

gram postive vs gram negative bacteria

Answer 25

-thick wall of peptidoglycan and lipoteichoic acid
-thin wall of peptidoglycan and an outer membrane containing phospholipids and lipopolysaccharides

Question 26

Bacteria have flagella, why?

Answer 26

generate propulsion to move the bacterium toward food or away from immune cells – chemotaxis

Question 27

Where do prokaryotes carry out ETC

Answer 27

cell membrane

Question 28

Which ribosomes are smaller, prokaryotic or eukaryotic

Answer 28

prokaryotic

Question 29

How do prokaryotes multiply?

Answer 29

binary fission: chromosomes replicates while the cell grows in size, until the cell wall begins to grow inward along the midline of the cell and divides it into two identical daughter cells

Question 30

Plamids

Answer 30

extrachromosomal material carried here, may contain antibiotic resistance genes or virulence factors.
integrate into genome-> episomes

Question 31

Bacterial genetic recombination increases bacterial diversity:

Answer 31

transformation: genetic material from surroundings is taken up by cell, which can incorporate this material into its genome

conjugation: transfer of genetic material from one bacterium to another across a conjugation bridge: plasmid F+ to F- cells

Transduction: transfer of genetic material from one bacterium to another via a bacteriophage vector

Transposons: genetic elements that can insert into or remove themselves from a genome

Question 32

Bacterial growth stages:

Answer 32

lag: adapt to new local conditions
exponential: growth increases exponentially
-stationary: resources are reduced, growth levels off
-death: resources are depleted

Question 33

Viruses contain:

Answer 33

genetic material, a protein coat (capsid) and sometimes a lipid-containing envelope

Question 34

Viruses are ———-

Answer 34

obligate intracellular parasites, they cannot survive and replicate outside of the host cell

Question 35

Bacteriophage:

Answer 35

viruses that target bacteria, contain tail sheath, which injects the genetic material into a bacterium, and tail fibers, which allow the bacteriophage to attach to the host cell

Question 36

What are viral genomes made of?

Answer 36

-various nucleic acids:
-DNA or RNA and may be single or double stranded

-Single stranded RNA– positive sense or negative sense

Question 37

Retroviruses;

Answer 37

contain a single-stranded RNA genome, from which a complementary DNA strand is made using reverse transcriptase

Question 38

How do viruses infect cells?

Answer 38

attach to specific receptors, and can then enter the cell by fusing with the plasma membrane, being brought in by endocytosis or injecting their genome into the cell

Question 39

How do viruses reproduce?

Answer 39

replicating and translating genetic material using the host cell’s ribosomes, tRNA, amino acids, and enzymes

Question 40

Bacteriophages 2 life cycles:

Answer 40

lytic cycle: bacteriophage produces massive numbers of new virions until the cell lyases– virulent
lysogenic cycle: virus integrates into the host genome as a provirus or prophage, which can then reproduce along with the cell. can remain here indefinitely or may leave genome in response to a stimulus and enter lytic cycle

Question 41

Prions and Viroids:

Answer 41

-infectious proteins that trigger misfolding of other proteins, usually converting a-helix to b-pleated sheet . Decreases solubility of protein and increases its resistance to degradation
-plant pathogens that are small circles of complementary RNA that can turn off genes, resulting in metabolic and structural changes and, potentially cell death