Cells Flashcards
How big are most cells? Why? What are 3 exceptions?
Typically 1-100 micrometers
Limited by large surface area to volume ratio; dependent on diffusion (spreading out) to move things in and out
More surface area → faster diffusion (takes a longer time to melt a bigger ice cube)
Exceptions:
Striated muscle fiber: in legs, long and thin, multiple nuclei (cells fused together), 30 mm
Aseptate hypha: in fungi, multiple nuclei, long and thin, cell wall and membrane, 30 mm
Giant alga: 1 nucleus, 100 mm
What are the 3 components of cell theory? Evidence? Pasteur’s experiment?
1) living organisms are made of cells
2) cells are the smallest unit of life
3) cells come from pre-existing cells
Evidence: see cells in microscope of many living things, nothing alive doesn’t have cells (yet)
Sterilized nutrient broth experiment:
Broth sterilized by boiling in flask
When exposed to air, microorganisms began to grow (3d component)
What are the 7 characteristics of living things? Viruses?
1) nutrition: obtain food from others / itself, provide energy for cell
2) metabolism: chemical reactions within cell, respiration to release energy
3) growth: irreversible size increase
4) response: react to change in environment (more spontaneous than evolution)
5) excretion: get rid of waste products of metabolism (emit CO2, poop)
6) homeostasis: keep internal conditions within tolerable limits (sweat, shiver)
7) reproduction: produce offspring
Viruses aren’t alive because they don’t metabolize
What are organelles? Size?
One of several formed bodies with a specialized structure and function
Identified using electron micrograph
Can be “membrane bound” in cytoplasm of eukaryotes
1-10 micrometers
Structure and function: nucleus, chloroplast, vacuole, rough er
Nucleus: control center, starts protein synthesis and mitosis
Nuclear membrane; center nucleolus that synthsizes ribosomes
Chloroplast: preforms photosynthesis, only plant cells, type of plastid (pigmented, green)
Connected round shapes with stacks of coins inside
Vacuole: compartmentalizes food and waste, protists have special ones, plants have large center vacuole with water
Membrane-bound
Rough enndoplasmic reticulum: site of protein synthesis, makes new membrane
Maze shape around nucleus, dotted with ribosomes
Structure and function: ribosomes, smooth er, golgi apparatus (sides?), mitochondria
Ribosomes: completes protein synthesis, made of RNA
Floating or on rough er
Smooth endoplasmic reticulum: delivers from rough er to golgi apparatus or outside of cell
Looks like rough er without dots
Golgi apparatus: modify and package molecules (especially for storage / secretion)
Round, unconnected layers called cistern(ae)
Cis side receives from rough er → cistern layer with unique enzyme reacts → travels in vesicle between layers → goes through more layers → ends at trans (shipping) side
Mitochondria: site of aerobic respiration (uses oxygen)
Shoeprint shape with lines
Structure and function: lysosome, centriole, cytoskeleton, cell membrane, cell wall
Lysosome: powerful digestive enzymes, can merge with food vacuole to digest, only animals
Hard to find: little circle with stuff
Centriole: helps with mitosis, makes spindle apparatus, only animals
Looks like a churro
Cytoskeleton: filaments that give cells shape
Long string in cytoplasm
Cell membrane: outside of cell, receive and transmit messages from environment and other cells, regulates what goes in / out
Cell wall: outer layer to maintain shape, plants only, protects from mechanical damage and excessive water
What are the similarities and differences of prokaryotes and eukaryotes?
Similarities: contain protoplasm (cytoplasm), cell membranes, ribosomes, DNA
Differences:
All prokaryotes are single cells, eukaryotes can be
Eukaryotic DNA associated with histon protein (wrapped), prokaryotic DNA is “naked”
Prokaryotes have no nuclei, mitochondria, membrane bound organelles
Prokaryotes have 70s ribosomes, eukaryotes have 80s
Eukaryotes differentiate (cells express genes differently for specialized function)
What are 3 metabolic activities of prokaryotes? How do they reproduce and diversify genes?
Metabolic activities: photosynthesis, fermentation (bread / kombucha), nitrogen fixation (cells in ground turn nitrogen into organic compounds for roots)
Divide asexually via binary fission (grow → pinch in half → 2 cells)
No genetic variety from reproduction, can come from conjugation (come together, exchange DNA, split)
Describe 7 features of the rod-shaped bacterium
Fimbriae: attachment structures on the surface of some prokaryotes; hair like
Nucleoid: region where cell DNA is located (no membrane); jumbly rod
Ribosomes: complexes that synthesize proteins; dots
Plasma membrane: membrane enclosing cytoplasm; innermost outer layer
Cell wall: rigid structure outside of plasma membrane; middle outer layer
Capsule: jelly-like outer coating on many prokaryotes; outermost outer layer
Flagella: locomotion organelles of some bacteria; tentacle-y strands
What is the fluid mosaic model and structure of cell membranes?
Fluid mosaic model: fluid → moving in plane; mosaic → collage (many parts)
Phospholipid bilayer: main structure of plasma membrane
Made of individual polar phospholipids (hydrophilic head with 2 hydrophobic tails)
Line up in 2 rows with tails together; heads touch watery cytoplasm or tissue fluid
Individual phospholipids may exchange places within row, rarely change over hydrophobic zone
What do cholesterol and 3 main proteins do in the cell membrane? What are the 5 protein functions?
Cholesterol (zig-zag molecules)
Stabilizers: if warm, cholesterol’s bulk limits fluidity by restraining movement; if cold, hinders solidification by preventing close packing
Glycoproteins
Carbohydrate bound into protein
Integral proteins (transport proteins) Go all the way through bilayer; hydrophilic ends and hydrophobic center
Peripheral proteins
Outside or inside, not embedded
Protein functions:
1) hormone (molecule traveling via blood to another part of body where it effects) bonding site; protein bonds to hormone as it goes by
2) immobilized enzymes: enzyme in membrane can catalyze reactions if there’s a molecule
3) cell adhesion: stick to cells of the same type
4) cell to cell communication: many calls travel around body in blood, tells cells “this needs to be carried off” etc
5) transport in / out of cell
What are the 3 types of passive transport?
Passive transport: no needed energy, molecules move down concentration gradient
Diffusion: tendency of molecules of any substance to spread out in available space
Oxygen and CO2 in membranes: low oxygen concentration in cell → diffuse from blood to cell; CO2 is a waste product in all, diffuses to blood
Osmosis: diffusion of water over partially permeable membrane (selective membrane)
Moves from lower → higher concentration to equally dilute
Facilitated diffusion: molecules or ions go through integral proteins (channels) instead of through membrane (glucose)
What is active transport? Two examples
Active transport requires energy to pump solids up / against the concentration gradient
Energy from ATP (adenosine triphosphate)
Requires integral protein through membrane → naturally selective shape for specific molecule
Sodium-potassium pump (animal nerve cells)
Sodium enters cell using ATP, potassium leaves cell; to fire nerve
Algae iodine pump
Iodine from ocean pumped into cell (inside 2x10^6 more concentrated)
What are the 2 types of large molecule transport?
Large molecule transport: active; won’t fit in integral protein
Endocytosis
Vesicles formed inside cell by pinching off membrane
How amoeba and paramencia eat food; white blood cells engulf and digest pathogens
Phagocytosis (food) or pinocytosis (liquid)
Exocytosis
Vesicle fuses with membrane and releases contents outside of cell
Paramecia contractile vacuole: osmosis pushes pond water into cell → collect water in vacuole → push water out via exocytosis (otherwise explode)
