Lecture 6 Flashcards
do all cells have ribosomes
yes (they are not organelles)
what is the cytoplasm
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.
what is the Cytosol
Cytosol: fluid part of the cytoplasm.
2 cell types?
Prokaryotic
Eukaryotic
unicellular or multicellular? Bacteria, Archaeans
All are unicellular
unicellular or multicellular? animals and plants
all are multicellular
unicellular or multicellular? fungus
some unicellular
most multicellular
unicellular or multicellular? protists
many uni
many multi
diff between eukaryotics and prokaryotics
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
what do all cells have in common
- Surrounded by a selective barrier: plasma membrane
- Filled with cytoplasm cyto=cells
- Have a cytoskeleton
- Have ribosomes (they are not organelles)
- Contain chromosome(s): DNA + protein
Bacterial cells are about … smaller than eukaryotic cells
10x
All cell membranes are…
fluid. Fluid boundary
what is the plasma membrane
The cell membrane that forms the boundary between the inside & outside of the cell is called a plasma membrane.
what is the cell membrane
The cell membranes that are part of organelles are simply called cell membranes
All cell membrane have … layers: mostly …
All cell membrane 2 layers: mostly phospholipid
the structure of plasma membrane
Phospholipid bilayer (head, tails, tails, head) Proteins, lipids can move within the membrane
Functions of plasma membrane
- Keeps each cell intact: boundary
- Cell-to-cell contact: needed to form tissues
- Cell-to-cell recognition: one cell recognizes another based on proteins present on the cell surface (ex immune response)
- Cell signaling (communication): one cell releases chemicals that bind to receptors in the plasma membrane of another cell. Ex receptors for hormones, neurotransmitters
- Movement of molecules into/out of cell
Selectively permeable
membranes have Selective permeability, how could huge molecules pass through it?
ex. aa or glucose: Need transporters (proteins) to pass through. Transcription and translation to make them
how do membranes choose what passes through
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
what goes into cells
Nutrients: sugars, aa, fa, O2, ions, vitamins…
Some hormones
what comes out of cells
Metabolic wastes like CO2
Hormones, enzymes, neurotransmitters, ions…
function of cytoskeleton
- Mechanical support & maintains cell shape
- Cell motility
Move entire cell (ex wbc) or parts of a cell ex organelles on “train tracks”, plasma membrane during phagocytosis) - Anchor organelles & enzymes
- Cell division
what is Microvilli
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
what is Cilia
move molecules over surface, ex in respiratory tract, or move entire cell, ex paramecium
what is Flagella
move entire cell, less numerous than cilia
function of Cell walls
Protects the cell
Maintains its shape
Prevents excessive uptake of water (Water goes inside (osmosis) and explodes. (osmotic pressure)
smallest alive unit ?
cells
do all cells have Cytoskeleton
yes.
how many chromosomes do prokaryotes usually have
one.
How big are eukaryotic cells
There’s a wide range, but the average is about 10-100 µm
what are phospholipids (membrane) made up of
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).
diff between cilia to flagella to microvilli
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
importance of the extracellular matrix
Provide support, nutrients, & can affect gene expression
