Cell Structure and Function

prokaryotic cells

simple cell

no nucleus, no membrane bound organelles - genetic information found in nucleoid region

circular chromosome

divide through binary fission

only found in Monera (bacteria) kingdom.

binary fission

duplicate genetic material, divide in half, produce two identical daughter cell

eukaryotic cells

has nucleus

can be unicellular or multicellular

linear chromosomeand membrane-bound organelles

endosymbiotic theory

eukaryotic cells originated from partnership of prokaryotes, focusing on mitochondria and chloroplasts

-same size as eubacteria

-reproduce like prokaryotes

-ribosomes similar to prokaryotes than eukaryotes

archezoa and diplomonads

eukaryotes without mitochondrias - Giardia is an infectious agent for the stomach

prokaryote organelles

plasma membrane, cell wall, ribosomes

cell/plasma membrane

phospholipid bilayer - “fluid mosaic model”

barrier around the cell

cell wall

present in all prokaryotes

barrier that shapes and protects cell

ribosomes (prokaryotes)

host organelle for protein synthesis

cytoplasm

large and small subunit

eukaryotic organelles

cell/plasma membranes, cell walls (some), ribosomes, smooth ER, rough ER, golgi apparatus, mitochondria, lysosomes (some), nucleus, vacuole, peroxisomes, chloroplasts (some), cytoskeleton

ribosomes (eukaryotes)

bound organelles form proteins to be exported to membrane

free ribosomes in cytoplasm to form proteins for cytoplasm

built in nucleolus

smooth ER

lipid synthesis, detox, and carboyhrate metabolism

no ribosomes on surface of cytoplasmic cells

a lot in liver

rough ER

ribosomes on surface of cytoplasmic cells

proteins sent to Golgi

golgi apparatus

vessicle from ER and carry proteins around golgi sacs

macromolecules sent for modification, adding sugars and other molecules for glycoproteins

proteins sorted and sent to final destinations

protein path

1. nucleus sends out mRNA to ribosome

2. ribosome reads mRNA, creates polypeptide

3. polypeptide sent to ER, becomes vessicle for Golgi

4. Golgi sorts proteins and sent to final destination

mitochondria

double membrane organelles

inside is matrix, folds are cristae - increased surface area is more room for ETC

Krebs cycle (matrix) oxidative phosphorylation (cristae)

breakdown sugar to produce ATP, aerobic cellular respiration

has its own DNA, ribosomes, membrane

lysosome

digestion, enzymes to break down macromoleucles

stomach of the cell

absence leads to storage diseases like Tay-Sachs

cells no longer needed are destroyed

nucleus

storage site of DNA and how to build proteins

contains ribosome

has own membrane - nuclear envelope

nuclear pores - mRNA and others to enter and exit

vacuole

storage

large in plants, small in animals

peroxisomes

contain enzymes for breaking down fatty acids and detoxifying harmful substances

make hydrogen peroxide as by product and turn it into water

chloroplast

photosynthesis and energy production for plants

light energy → chemical energy

inner is stroma (light independent reactions), dark

outer is thylakoid membrane (light dependent reactions), light

has own membrane, ribosome

cytoskeleton

structure of cell

has microtubules, microfilaments, intermediate filaments

microtubules: separate cells in cell division and movement of particles (flagella and cilia)

microfilaments: muscular contraction

intermediate filaments: keratins, maintain position of organelles

animal vs. plant

animals dont have chloroplasts or cell walls

plants dont have centrioles

fluid mosaic model

integral proteins, peripheral proteins, glycolipids, glycoproteins

integral proteins

embedded in membrane

some can be transport/channel

can also function as enzymes to speed up rate of cellular reactions

peripheral proteins

on one side of cell membrane

receptor proteins - signaling and attachment from molecule

glycolipids & glycoproteins

surface of cell membrane

receptors on cell surfaces

immune response

permeability of membrane

semi-peremable

small, non-charged molecules

basic types of cell transport

diffusion, osmosis, facilitated diffusion, active transport, endocytosis, exocytosis

diffusion

movement of molecules down concentration gradient without use of energy

high concentraiton → low concentration

passive

osmosis

passive diffusion of water down concentration gradient

high concentraiton → low concentration

water goes hypotonic (swell, low solute) to hypertonic (shrink, high solute)

isotonic is middle ground, ideal for animals

hypotonic is ideal for plants

facilitated diffusion

like diffusion but with help of channel/transport proteins

specific

active transport

against concentration gradient, so low → high

requires ATP

NaK pump: diffusion wants Na in and K out—pump moves Na out and K in, maintaining cell potential

affected by temp, number of transport molecules, ATP, and ion concentration

endocytosis

membrane folds in to form vessicle and escorts into cell

phagocytosis and pinocytosis

receptor-mediated endocytosis: receptor brings in molecule

active transport

exocytosis

exported out of the cell, vessicle becoming part of cell membrane

active transport

water potential

how freely water molecules can move

determining water potential

a. cell walls exert pressure in opposite direction of turgor

b. predict water movement from solute potential

c. add presure + solute potential

turgor/pressure potential

physical pressure on cell membranes, increases with increasing pressure

solute potential

decreases as concentration of solute increases