Week 2- Cells

Question 0

Describe a eukaryote cell

Answer 0

“True nucleus”
Has a distinct nucleus
Has a nuclear envelope
Contains chromosomes (DNA + protein)

Question 1

Describe a prokaryote cell

Answer 1

“Before nucleus”
Contains a single strand of DNA
Does not contain a nucleus
Free-floats in gelatinous protoplasm

Question 2

Why aren’t cells very big?

Answer 2

Relationship between cell surface area & volume. If a cell were larger, it wouldn’t be able to take in nutrients fast enough to feed itself and would die.

Question 3

Describe the cell membrane.

Answer 3

Aka plasma membrane or plasmalemma
Separates cell from its environment
Controls what goes in & what goes out

Question 4

Describe cytoplasm

Answer 4

Everything inside the cell membrane except the nucleus and genetic material.
Colloidal protoplasm
Composed of proteins, electrolytes, metabolites, flexible cytoskeleton and organelles.

Question 5

Describe a virus

Answer 5

Composed of a protein covered capsule
Contains either one strand of DNA or one strand of RNA
Parasitic- lacks biochemical mechanisms to reproduce
Relies on cells for nutritional, structural and molecular assistance to multiply
Attaches to cell’s surface & injects its genetic material into the cytoplasm (interferes with cells normal metabolic processes)
Cells are reprogrammed to manufacture viruses
Cell ruptures (dies), releasing hundreds of newly formed viruses into extracellular environment
Considered to be alive ( able to reproduce, grow, develop, adapt, respond to stimuli and maintain a stable environment using energy from their environment

Question 6

Describe a prion

Answer 6

Not considered to be alive
Believed to be proteins or proteinaceous infective particles
Lack DNA and RNA
All known prion diseases are fatal and cause a progressive neurodegenerative disorder(leaves grossly visible holes in the brain)
Condition is called spongiform encephalopathy because affected brains resemble sponges.
Humans can contract prions by ingestion or inoculation.

Question 7

What does zoonotic mean?

Answer 7

That the disease can be transmitted between animals and humans .

Question 8

Describe the lipid bilayer

Answer 8

The cell membrane is composed of two layers of phospholipid molecules arranged so that the hydrophilic heads are on the outside and the hydrophobic fatty acid tails are on the inside

Question 9

Hydrophilic

Answer 9

Attracted to water

Question 10

Hydrophobic

Answer 10

Repelled by water

Question 11

Integral proteins

Answer 11

Contact globular proteins that occur within the lipid bilayer

Question 12

Pores created by integral proteins

Answer 12

Channels within the protein molecule that allow substances such as water to pass through with no resistance make up approx 0.2% of the cell surface area

Question 13

Cell membrane selectivity

Answer 13

Most lipid soluble material (such as oxygen & carbon dioxide) pass through with ease
Ionized and water-soluble molecules (amino acids sugars and proteins) do not readily pass through
Globular proteins (integral proteins)form channels through which other molecules can pass some form selective passageways that only permit particular substances to enter or exit. others create pores

Question 14

Describe flagella

Answer 14

Originate from a pair of centrioles (basal bodies) located at the periphery of the cell (just under the plasmalemma) grow outwards from basal bodies and exert pressure on plasmalemma
 Occur singly
Are significantly longer than cilia
Propels the cell forwards by undulating
Moves cells through fluid

Question 15

Describe Cilia

Answer 15

Originate from a pair of centrioles (basal bodies) located at the periphery of the cell (just under the plasma membrane)
grow outward from basal bodies and exert pressure on plasma membrane
Occur in large numbers on exposed surface of some cells
Shorter than flagella 10 µm long
Move synchronously, one after the other, creating waves of motion that propel fluids, mucus and debris across cellular surface
Upper respiratory tract & oviduct

Question 16

Intracellular fluid

Answer 16

Water found inside the cell

Question 17

Extracellular fluid

Answer 17

Fluid outside the cell

Question 18

Interstitial fluid

Answer 18

Extracellular fluid specifically found in tissues rather that than in lymphatic or blood vessels

Question 19

Ions

Answer 19

Atoms with either a positive or negative electrical charge

Question 20

Cations

Answer 20

Atoms with a positive electrical

Question 21

Anions

Answer 21

Atoms with a negative electrical charge

Question 22

Electrolytes

Answer 22

Substances that have the ability to transmit an electrical charge

Question 23

PH

Answer 23

Measures acidity and alkalinity
Ranges from 1 (most acidic) to 14 (most alkaline)
Seven is neutral

Question 24

Diffusion

Answer 24

Kinetic movement of molecules from higher to lower concentration passive process ex: water, oxygen and carbon dioxide

Question 25

Facilitated diffusion

Answer 25

Selective carrier proteins assist in movement of molecules from higher to lower concentration speed of diffusion is limited by saturation of carrier molecules passive process ex: movement of glucose into muscle and fat cells

Question 26

Osmosis

Answer 26

Passive movement of water through a semipermeable membrane from dilute solution to a more concentrated one ex: water moves from stomach into bloodstream

Question 27

Semi permeable membrane

Answer 27

A membrane that allows some molecules to pass through but not others

Question 28

Concentration gradient

Answer 28

Spectrum between the most concentrated region and the area that is least filled with molecules

Question 29

Hypotonic

Answer 29

Lower osmotic pressure of two fluids | contains more solute than solvent

Question 30

Hypertonic

Answer 30

Higher osmotic pressure of two fluids | contains more solvent then solute

Question 31

Isotonic

Answer 31

Two fluids have equal osmotic pressure | solute and solvent are equally distributed

Question 32

Filtration

Answer 32

Pressure gradient liquids maybe push through a membrane if the pressure (hydrostatic pressure) on one side is greater than that on the other side

Question 33

Hydrostatic pressure

Answer 33

Force that pushes a liquid ex: blood pressure generated by the pumping heart forces blood through vessels and minute capillaries small molecules and cells may be pushed through but large cells may not ex: in the kidney blood is filtered through specialized capillaries in the process of making urine

Question 34

Active transport

Answer 34

Relies on a carrier protein with a specific binding site does not require concentration gradient All cells demonstrate active transport of electrolytes (sodium, potassium, calcium and magnesium) specialized cells can transport iodide, chloride and iron needs ATP

Question 35

Symport system

Answer 35

All substances are moved in the same direction

Question 36

Antiport system

Answer 36

Some substances are moved in one direction and others are moved in the opposite direction

Question 37

Cytosis

Answer 37

Mechanism for bringing nutrients into the cell and ejecting waste requires ATP active process 2 types: endocytosis- going into the cell exocytosis- going out of the cell

Question 38

Phagocytosis

Answer 38

Cell eating Cell engulfs solid material Vesticle formed is a phagosome

Question 39

Pinocytosis

Answer 39

Cell drinking | cell engulfs liquid

Question 40

Excretion

Answer 40

Cells export waste substances from intracellular environment into extracellular space by exocytosis

Question 41

Secretion

Answer 41

Exocytosis of manufactured molecules

Question 42

Sodium potassium pump mechanism

Answer 42

Sodium and potassium ions are transported in and out of cells against their concentration gradients (antiport system) carrier molecule located in the plasma membrane accommodates three sodium ions ATP energy binds to carrier molecule and releases energy by breaking off one phosphate (adenosine diphosphate remains) for each molecule ATP one carrier protein can transport three sodium and two potassium Carrier protein returns to its original shape when transport of molecules is complete Three sodium and one ATP bind to carrier protein ATP releases energy, carrier protein changes shape and releases three sodium out of cell two potassium molecules bind to carrier protein carrier protein resumes original shape, releasing sodium potassium and one phosphate into cell