Cellular Biology - Midterm 2 Flashcards by Catherine Anaya

Prokaryotes
- peptidoglycan
- pili
- binary fission

Unicellular
Small
No nucleus
Circular DNA
No organelles / cytoskeleton
Small ribosomes
Peptidoglycan: cell walls
Flagella rotates using H+ gradient
Has pili: for adhesion and sexual exchange
Binary fission: how prokaryotes divide
ex) bacteria and archaea

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Eukaryotes
- mitosis and meiosis

uni/multicellular
Larger
Contains nucleus w/ DNA
DNA as linear chromosome protein complex
Many organelles
3 types of fibers in cytoskeleton
Large ribosomes
Cell walls in plant cells (cellulose) and fungi (chitin)
Flagella move in whip-like motion , composed of microtubules
No pili
Mitosis and meiosis: how eukaryotes divide
ex) animals, fungi, plants, protists

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Schekman

discovered genes important for protein secretion by studying yeast

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Fleming

discovered antibiotic penicillin

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Van Leeuwenhoek

believed sperm cells contained mini humans

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Nucleus
- chromosomal DNA

Double membrane organelle
Holds all chromosomal DNA: packed chromatin fibers with equal mass of protein histine
Communicates with cystol

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Nucleolus

assembles ribosomes

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nuclear envelope

double membrane supported by nuclear lamin

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nuclear pores
- NLS
- importin

Nuclear pores: allow transport in / out of nucleus
NLS: amino acid tag required for transport
Importin: recognizes amino acid tag

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Mitochondria
-inner membrane
- cristae
- matrix

Creates ATP (energy)
Double membraned organelle
Inner membrane: folded into cristae to increase surface area, site of electron transport
Matrix: site of TCA cycle, contains many enzymes

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chloroplasts
- thylakoid
- grana
- stroma

Double membrane organelle
Found in plants only
Conducts photosynthesis
Thylakoid: where light rxns occur
Grana: stacks of thylakoids
Stroma: where dark rxns occur (ex: sugar synthesis)

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endosymbiosis

engulfed prokaryotes, resulted in mitochondria and chloroplasts

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centriole

( only in animal cell) organizing center for facilitating cell division

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Plant cell
Cell wall:
Chloroplast:
Vacuole:

structural support
: for photosynthesis
: storage and provides turgor pressure

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Plasma Membrane

phospholipid bilayer surrounding cell
Contains proteins that allow for transport in / out of the cell

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Endoplasmic reticulum

Specializes in synthesis and transport of lipids and membrane proteins

rough er

engaged in protein synthesis; has ribosomes

SMOOTH ER

lipid metabolism, detoxifies toxins; no ribosomes

lysosomes

Single membrane vesicle
Intracellular digestion

Peroxisomes

Single membrane vesicle
Generate and destroy hydrogen peroxide

Endomembrane System

ER + golgi + lysosomes + peroxisomes

cytoskeleton

Array of protein filaments in cystol that give cell shape and movement
Include microtubules, microfilaments, and intermediate filaments

microfilaments (actin filaments)
- pseudopodia
- cytokinesis

Largest filament
Double helix structure
Polar
Actin subunit
Resists pull tension
Pseudopodia: moves cells via cell crawling
Cytokinesis: divides animal cells in two
determine shape
whole cell movement

intermediate filaments

Keratin / lamin fibers wound into thicker cables
Intermediate sized filament
Resists pull tension
Anchor nucleus and other organelles

microtubules

Polar hollow tube composed of alpha and beta tubulin dimers Determine position of membrane bound organelles and direct intracellular transport

Dynamics - treadmilling - dynamic instability

Microtubules and actin filaments are dynamic Treadmilling: net growth at one end, shortening at other end (both MT’s and MF’s) Dynamic instability: switching between growing and shortening (only MT’s)

cilia

hair like particle responsible for movement in wavelike motion, usually many per cell

flagella

responsible for movement in propeller motion, usually only a couple per cell

dyenin motors

move cilia and flagella - attached permanently to microtubule - use ATP as energy source - move towards - end

KInesin

another motor molecule - walks along microtubules - use ATP and myosin as energy - move towards + end

cell membranes - integral protein - peripheral protein

Phospholipid bilayer with cholesterol to control fluidity Contains membrane proteins to regulate movement in / out of the cell Integral protein: penetrates bilayer (channels, receptors) Peripheral protein: anchors on bilayer surface

Passive transport - simple diffusion - facilitated diffusion

Spontaneous, requires no energy Materials move DOWN gradient (from area of higher to lower concentration) Simple diffusion : move directly across membrane (ex: liquids, small uncharged molecules) Facilitated diffusion: involves channel / carrier protein (large mcls, ions, polar molecules) Gated process: opens / closes w ligand signal

active transport - 1o active transport - 2o active transport (antiport / symport)

Requires E (ATP / ion gradient) Moves against gradient using pump 1o active transport: directly uses ATP to pump molecule in or out 2o active transport: coupled transport using concentration gradient Antiport: 2 solutes move in opposite directions Symport: 2 solutes move in same direction

endocytosis - phagocytosis - pinocytosis - receptor mediated

Uptake items via vesicle formation Phagocytosis: uptake of particles Pinocytosis: uptake of fluids Receptor mediated : uptake of specific item (ex: LDL uptake)

LDL Uptake steps

LDL particle binds with coated pit Clathrin vesicles form Vesicles become uncoated Vesicle fuses with lysosomes Lysosomes digest LDL and release cholesterol

protien trafficking

Ribosome attaches to ER with protein Protein is inserted into ER during translation Signal sequence is removed from protein Vesicle transports protein to golgi (enters on cis face) Protein is modified in golgi Protein leaves golgi on trans face in transport vesicle Protein is released from cell via exocytosis