Lecture 6

Question 1

do all cells have ribosomes

Answer 1

yes (they are not organelles)

Question 2

what is the cytoplasm

Answer 2

Cytoplasm: everything inside the cell, except for the nucleus.
Does not include the plasma membrane.

The cytoplasm is where the chemical reactions of a cell take place.

Question 3

what is the Cytosol

Answer 3

Cytosol: fluid part of the cytoplasm.

Question 4

2 cell types?

Answer 4

Prokaryotic

Eukaryotic

Question 5

unicellular or multicellular? Bacteria, Archaeans

Answer 5

All are unicellular

Question 6

unicellular or multicellular? animals and plants

Answer 6

all are multicellular

Question 7

unicellular or multicellular? fungus

Answer 7

some unicellular

most multicellular

Question 8

unicellular or multicellular? protists

Answer 8

many uni

many multi

Question 9

diff between eukaryotics and prokaryotics

Answer 9

PROKARYOTIC organisms:

• No organelles: ex DNA not in a nucleus
• Genomic DNA: (1) circular chromosome
• All are unicellular (single-celled), but some can stick together to form colonies

EUKARYOTIC organisms

• Organelles, including a nucleus, are present
• Genomic DNA: multiple linear chromosomes
• Some are unicellular, others are multicellular

Question 10

what do all cells have in common

Answer 10

1. Surrounded by a selective barrier: plasma membrane
2. Filled with cytoplasm cyto=cells
3. Have a cytoskeleton
4. Have ribosomes (they are not organelles)
5. Contain chromosome(s): DNA + protein

Question 11

Bacterial cells are about … smaller than eukaryotic cells

Answer 11

10x

Question 12

All cell membranes are…

Answer 12

fluid. Fluid boundary

Question 13

what is the plasma membrane

Answer 13

The cell membrane that forms the boundary between the inside & outside of the cell is called a plasma membrane.

Question 14

what is the cell membrane

Answer 14

The cell membranes that are part of organelles are simply called cell membranes

Question 15

All cell membrane have … layers: mostly …

Answer 15

All cell membrane 2 layers: mostly phospholipid

Question 16

the structure of plasma membrane

Answer 16

Phospholipid bilayer (head, tails, tails, head)
Proteins, lipids can move within the membrane

Question 17

Functions of plasma membrane

Answer 17

1. Keeps each cell intact: boundary
2. Cell-to-cell contact: needed to form tissues
3. Cell-to-cell recognition: one cell recognizes another based on proteins present on the cell surface (ex immune response)
4. Cell signaling (communication): one cell releases chemicals that bind to receptors in the plasma membrane of another cell. Ex receptors for hormones, neurotransmitters
5. Movement of molecules into/out of cell
   Selectively permeable

Question 18

membranes have Selective permeability, how could huge molecules pass through it?

Answer 18

ex. aa or glucose: Need transporters (proteins) to pass through. Transcription and translation to make them

Question 19

how do membranes choose what passes through

Answer 19

Chemical properties determine what enters directly:
Small molecules pass through.
Membrane mostly lipid, so lipid-soluble molecules can pass.

Transporters are specialized proteins: channels or carriers are present for certain but not all molecules.

Bulk transport mechanisms: endocytosis, exocytosis

Everything else is excluded

Question 20

what goes into cells

Answer 20

Nutrients: sugars, aa, fa, O2, ions, vitamins…

Some hormones

Question 21

what comes out of cells

Answer 21

Metabolic wastes like CO2

Hormones, enzymes, neurotransmitters, ions…

Question 22

function of cytoskeleton

Answer 22

1. Mechanical support & maintains cell shape
2. Cell motility
   Move entire cell (ex wbc) or parts of a cell ex organelles on “train tracks”, plasma membrane during phagocytosis)
3. Anchor organelles & enzymes
4. Cell division

Question 23

what is Microvilli

Answer 23

folds of plasma membrane that serve to increase surface area of cell: for absorption or secretion.

microvilli increases surface area to volume ratio in cells

Question 24

what is Cilia

Answer 24

move molecules over surface, ex in respiratory tract, or move entire cell, ex paramecium

Question 25

what is Flagella

Answer 25

move entire cell, less numerous than cilia

Question 26

function of Cell walls

Answer 26

Protects the cell Maintains its shape Prevents excessive uptake of water (Water goes inside (osmosis) and explodes. (osmotic pressure)

Question 27

smallest alive unit ?

Answer 27

cells

Question 28

do all cells have Cytoskeleton

Answer 28

yes.

Question 29

how many chromosomes do prokaryotes usually have

Answer 29

one.

Question 30

How big are eukaryotic cells

Answer 30

There's a wide range, but the average is about 10-100 µm

Question 31

what are phospholipids (membrane) made up of

Answer 31

1 head + 2 fatty acid tails The hydrophilic heads are in contact with fluid outside and inside the cell while the hydrophobic tails stay with each other (avoid fluid).

Question 32

diff between cilia to flagella to microvilli

Answer 32

microvilli ABSORPTION: increase the surface area of the membrane so more nutrients get absorbed, do not move cilia MOVE (eyelash): move particles in body flagella MOVE(tail, sperm): whip back and forth

Question 33

importance of the extracellular matrix

Answer 33

Provide support, nutrients, & can affect gene expression