Ch. 3 - Cells

3 main parts of a generalized cell

nucleus - contains DNA

cytoplasm - cytosol and organelles

plasma membrane - outer boundary

describe plasma membrane structure

phospholipid heads are pointed towards the ICF and ECF, making it an oil consistency, cholesterol stabilizes the bilayer by decreasing movement, glycocalyx (glycolipids/proteins) - lipids and proteins attached to sugars (cell markers, sugary coat around membrane)

what major fluid compartments does the plasma membrane seperate?

intracellular fluid and extracellular fluid

why is the plasma membrane referred to as a “fluid mosaic”?

because it has an olive oil consistency, and it is made up of different parts

why is the plasma membrane referred to as “selective” and “dynamic”?

it picks and chooses what to let in, and it can change what it lets in

six main functions of membrane proteins

transport, receptor, cytoskeleton, enzyme, intercellular joining, cell-cell recognition

three main types of cell-cell junctions, what are their functions? where are they found, and how does that make sense?

tight junctions - prevent substances getting in between cells, stomach, intestines, bladder (urine, acid, etc.)

desmosomes - prevents separation under tension, epidermis (stretching/pulling)

gap junctions - allows cell communication, electrical + chemical, excitable tissues (muscle/nervous)

what is the major difference between active and passive transport?

active requires ATP

how does simple and facilitated diffusion work? what kinds of molecules use this transport?

simple can directly go through the bilayer (gases, vitamins, hormones) while facilitated requires a membrane protein (ions, simple sugars) - still high to low concentration

define osmosis… how does permeability affect it?

diffusion of water - if there’s a certain membrane protein, more water molecules can enter faster

describe what happens to cells in isotonic, hypertonic, and hypotonic solutions

isotonic - equal solute concentration, no water movement, normal size

hypertonic - greater concentration outside, water leaves cell, cell shrinks

hypotonic - lower concentration outside, water floods cell, cell swells

describe how active transport works, and how it can be used to indirectly drive the transport of of other molecules

they require ATP and carrier proteins to move solutes against their concentration gradient - primary transport uses energy directly from ATP breakdown, while secondary uses energy from ionic gradients that the primary made

what kind of membrane transport is utilized by the sodium-potassium ATPase pump? (passive/active transport? primary/secondary?)

primary active transport

what kind of membrane transport is utilized by a sodium/glucose transporter in the small intestine? (passive/active transport? primary/secondary?)

active secondary transport

some examples of how secondary active transport is used in the body

Na/glucose pump and Na/amino acid

three types of vesicular transport… passive/active?

endocytosis (substances into the cell), transcytosis (substances across the cell), and exocytosis (substances out of the cell) - all active

what is exocytosis? give some examples that use it

the transport of substances out of the cell - proteins in a vesicle brought to the edge and let out

mitochondria (functions)

site of ATP synthesis by aerobic repsiration

ribosomes (functions)

site of protein synthesis

rough ER (functions)

packages proteins in vesicles for golgi

smooth ER (functions)

site of lipid and steroid (cholesterol) synthesis

golgi apparatus (functions)

packages, modifies, and separates proteins to be exported from cell (put into lysosomes or plasma membrane, “traffic director”)

lysosomes (functions)

site of intracellular digestion, “demolition”

peroxisomes (functions)

detoxify harmful substances found in cell

cytoskeleton (functions)

supports cellular structures, machinery to generate cell movement

centrosome (functions)

cell’s microtubules organizing center

centrioles (functions)

organize a microtubule network during mitosis; form the bases of cellular extentions

nucleus (functions)

“control center”, contains cellular DNA, “blueprints” for protein synthesis

cilia (functions)

coordinated movement propels substances across cell surfaces, molecules can stick to it

flagella (functions)

propels the cell

overall mechanism of protein synthesis (name process DNA code transferred to mRNA code, name process mRNA code transferred to chain of amino acids, name where in the cell these take place)

transcription - converts DNA to mRNA in nucleus

translation - converts mRNA to protein, occurs in the ribosomes

if nucleotide sequence of DNA is: ATAGGACAT, what would be mRNA nucleotide sequence? what would be tRNA sequence? how many amino acids does this sequence for? would it be a di-, tri-, polypeptide or protein?

UAUCCUGUA as mRNA, the tRNA would split it in 3s, into 3 amino acids, which is a tripeptide

what does “there is redundancy in the genetic code” mean? why does an error in the DNA sequence not result in an error of the associated protein?

there is room for error, or a DNA silent mutation, because multiple sequences can code for the same amino acid

tRNA

brings the right amino acid to the ribosome (matches with triplet)