The cell/ Eukaryotes and Prokaryotes

Question 1

Describe eukaryotic cells

Answer 1

They have membrane bound organelles with the cell surrounded by the plasma membrane and the organelles surrounded by plasma membranes.

The cytosol is a fluid layer that allows for diffusion of molecules throughout the cell.

Question 2

Cell theory

Answer 2

Contains 4 rules for living things:
1. Cells are the basic unit of life.
2. Cells only come pre-existing cells
3. Cells contain DNA as the genetic material and is passed from parent to daughter cells
4. A living things are composed of cells

Question 3

Nucleus

Answer 3

Contains DNA which are packed into chromosomes. Nucleus are surrounded by the nuclear membrane ( or envelope) which is a double membrane that contains nuclear pores which allows for movement of materials to and from the nucleus.

Question 4

Nucleolus

Answer 4

subsection of the nucleus where ribosomal RNA is made.

Question 5

Mitochondria

Answer 5

Creates ATP for the cell via electron transport chain. Contains outer membrane and inner membrane with the space between them called the intermembrane space.

The inner membrane contains enzymes for E.C.T. and inside is called the matrix which are folded into cristae.

They have they’re own DNA ( EXACT copy of maternal DNA) and can divide via binary fission. They trigger apoptosis by releasing mitochondrial enzymes into cytoplasm.

Question 6

Lysosomes

Answer 6

Contains hydrolytic enzymes which breaks down cellular waste and products of endocytosis.

If these enzymes are released this can cause autolysis of the cell.

Question 7

Endoplasmic Reticulum ( ER)

Answer 7

Series of interconnected membranes that are continous with the nuclear envelope. Contains rough E.R. which contains ribosomes which makes proteins destined for secretion. Smooth E.R. doesn’t have ribosomes and serves a role in lipid synthesis and detoxification.

Question 8

Golgi apparatus

Answer 8

stacked membrane discs that serve to modify, package, and ship proteins to specific cellular destinations.

Question 9

Peroxisomes

Answer 9

Contains hydrogen peroxide that use beta-oxidation to break down long chain fatty acids.

Also create phospholipids and participates in the pentose phosphate pathway.

Question 10

What is the role of cytoskeleton? What are the 3 components?

Answer 10

They provide stability and support for the cell. Also serves a role in transport.

• Microfilaments- polymers of actin. Forms cleavage furrow in cell division. Interact with myosin to generate contraction force. Provide structural rigidity to cell. Makes up microvilli in animals.
• Microtubules- made of tublin protein. Serves role in movement of motor proteins and pulling apart of chromosomes during mitosis and meiosis. Forms cilia and flagella for movement.
• Intermediate filaments - made of various proteins. Resistant to tension. Serves role in integrity of cytoskeleton and cell-to-cell adhesion.

Question 11

Epithelial tissues

Answer 11

Cover the body and line it’s cavities. Protects against pathogen invasion and serves to absorb or secrete substance.

Functional part of organ is the parenchyma.

Question 12

Epithelial cells may be polarized what does this mean?

Answer 12

One side faces the lumen ( outside world) and the other side faces blood vessels.

Question 13

What are the classification of epithelia in terms of layers?

Answer 13

Simple - contains 1 layer of epithelial cells.

Stratified - has many layers of cells.

pseudostratified - appears to have multiple layers but only has one. Appears this way due to differences in height of epithelial cells.

Question 14

What are the classification of epithelia cells ( in terms of shape)?

Answer 14

• Cubodial cells- cube shaped cells.
• columnar- long and thin.
• squamous- flat and scalelike.

Question 15

Role of connective tissues

Answer 15

Serves to support cells and provide a place to reside and carry out functions.

• Forms the stroma which is a support structure to secrete materials that forms the extracellular matrix.
• Bone, cartilage, tendons, ligaments, adipose tissue, and blood are all connective tissue.

Question 16

Why are viruses not considered living?

Answer 16

Because they violate cell theory. They’re acellular, can contain RNA as genetic material, and need host to reproduce.

Question 17

How do prokaryotes organize their DNA?

Answer 17

They organize it into a double stranded circular DNA located in the nucleoid region.

Question 18

Archea v. prokaryotes v. eukaryotes

Answer 18

Archea are similar in all aspects to bacteria except archea doesn’t have peptidoglycan in their cell walls. They also tend to be extremophiles.

Prokaryotes doesn’t have membrane bound organelles but have a cell membrane and plasma membrane.

Eukaryotes has membrane bound organelles.

Question 19

What are the 3 shapes of prokaryotes?

Answer 19

Cocci– spherical bacteria
bacilli- rod shaped bacteria
spirilla- spiral shaped bacteria

Question 20

Obligate aerobes

Answer 20

bacteria that can only use oxygen for metabolic processes.

Question 21

Obligate anerobes

Answer 21

Cannot use oxygen for metabolic purposes.

Question 22

Faculative anaerobes

Answer 22

can switch between using oxygen or another source for metabolism, depends on what’s avaliable in the environment.

Question 23

Aerotolerant anaerobes

Answer 23

Cannot use oxygen for metabolism but can survive in oxygen-containing environments.

Question 24

The cell wall and plasma membrane of bacteria forms what?

Answer 24

The envelope which determines what enters and exists the bacterium.

Question 25

Gram- positive v. Gram- negative bacteria

Answer 25

We can categorize bacteria into 2 groups based on their cell wall when we stain them with crystal- violet followed by safranin.

• Gram-negative bacteria has thin cell wall made of thin cell wall made of peptidoglycan and an outer membrane composed of phospholipids and lipopolysaccharides. Stains pink.
• Gram- positive bacteria - has thick cell wall made of peptidoglycan + lipoteichoic acid. Stains purple.

Question 26

Chemotaxis

Answer 26

Movement of bacteria in response to chemical stimuli.
Flagella made of flagellin in bacteria.

Question 27

How do prokaryotes replicate?

Answer 27

Binary fission

Question 28

Plasmids

Answer 28

Located in bacteria and doesn’t contain DNA they have antibiotic resistance genes and can have virulence factors.

Plasmids that can be incorporated into bacteria DNA are called episomes.

Question 29

What are the 3 forms of genetic recombination in bacteria?

Answer 29

• Transformation- bacteria incorporates genetic material from the environment.
• Conjugation- transfer genetic material from one bacterium to another via a conjugation bridge. Conjugation bridge is encoded by the F plasmid which contains the sex factor gene.
• Transduction - viruses ( bacteriophage) transport genetic material from one bacterium to another. When it infects the other bacterium the genetic material is transfered.

Question 30

Transposons

Answer 30

When genetic material is removed and injected somewhere else in the genome. Can cause mutations.

Question 31

Asexual reproduction

Answer 31

Reproduction without sex. Includes binary fission and budding.

Question 32

What are the role of plasmids experimentally?

Answer 32

They use them to clone, manipulate, and transfer gene. Thus they’re called vectors.

Components of vectors needed:
- ORI- origin of replication needed for replication of vector.
-Restriction enzyme- needed to add in the gene of interest.
- Need host transcription initiating sequence.

DOESNT NEED: Reporter gene which allows us the identify the plasmid.

Question 33

Signal recognition particle (SRP)

Answer 33

Steers the ribosome to the ER and threads the protein through the RER.

Question 34

Signal peptide (signal sequence)

Answer 34

Present at the N- terminus of newly synthesized proteins, it sets them to the secretory pathway. If they don’t have this signal peptide it will accumulate in the cytoplasm.

Question 35

Negative sense RNA v. Positive sense RNA

Answer 35

Negative sense RNA is RNA of a virus that must be copied before it can be translated into a protein.

Positive sense RNA is RNA of a virus that can be directly translated into protein.