cell structure and function : unit 2

prokaryotic cell

• DO NOT contain a nucleus (free floating DNA).

• No membrane bound organelles

• Small, simple, single celled

• Bacteria and Archaea Capsule

eukaryotic cell

• DO contain a nucleus.

• Has membrane bound organelles.

• Larger, more complex, single or multicellular

• Animals, Plants, Protists,
  Fungi

animal cell has

• No cell wall

• Contains centrioles and lysosomes

• Numerous small vacuoles.

• Less structured.

plant cells

• Has a cell wall

• Chloroplasts

• Central Vacuole

• Organized and structured

cell wall picture

cell wall describes

Rigid structure made of complex carbohydrates providing a permeability barrier to move some sunstances; found in plants, fungi, some protists, and bacteria

cell membrane picture

cell membrane describe

Phospholipid bilayer that surrounds the cell; Regulates what comes into and out of the cell and protects the cell interior from the extracellular

space.

ribosome picture

ribosome describe

Composed of protein and Ribosomal RNA (rRNA)

Ribosomes "read" messenger

RNA (mRNA) to synthesize proteins.

cytoplasm picture

cytoplasm describe

Fluid within the cell to help maintain cell shape and is the site of many metabolic chemical reactions.

cytoskeleton

centrioles

flagells and cilia

nucleus

Houses the cell's DNA and directs the synthesis of ribosomes and proteins.

nucleolus

Site of ribosome and rRNA synthesis in the cell.

rough endoplasmic recticulum

Folded organelle with ribosomes attached; responsible for synthesizing and packaging proteins to the golgi apparatus.

smooth endoplasmic reticulum

Responsible for lipid/hormone synthesis and detoxification of cell wastes.

golgi apparatus

Responsible for:

• Helping fold and modify proteins

• Packaging proteins/lipids into vesicles

• Sending these vesicles to their intended intra- or extracellular destination

  

lysosome

peroxisome

Carry out oxidation reactions that break down fatty acids and amino acids; detoxify many poisons that enter the body.

vacuole

Membrane-bound sacs that function in storage and transport.

lysosomes are bigger than peroxisomes

lysosomes are bigger than peroxisomes

mitochondria

• Responsible for some of the processes that synthesize

ATP.

• Has two membranes, which allows for compartmentalization of different chemical reactions.

chloroplast

• Responsible for performing photosynthesis in autotrophs.

• Has two membranes, which allows for compartmentalization of different chemical reactions

why are organelle membranes folded to increase surface area?

More surface area = more space to do work

Membranes are where chemical reactions happen — so more membrane = more reactions can happen at once.

endosymbiotic theroy evidence

1. Double Membrane 🔵🔵

• Both mitochondria and chloroplasts have two membranes

• The inner membrane = original bacterial membrane

• The outer membrane = from when the host cell engulfed it

• No other organelles have double membranes this way

2. Their Own DNA 🧬

• Both have their own circular DNA

• Circular DNA is a bacterial trait — NOT how eukaryotic DNA looks

• They carry genes separate from the nucleus

3. Their Own Ribosomes 🔬

• Both have their own ribosomes

• These ribosomes are 70S — same size as bacterial ribosomes

• Eukaryotic ribosomes are 80S — different size

• This is a huge piece of evidence!

4. They Reproduce Like Bacteria 🔄

• Mitochondria and chloroplasts divide by binary fission

• Same way bacteria reproduce — NOT how organelles normally replicate

5. Similar Size to Bacteria 📏

• Both organelles are roughly the same size as modern bacteria

The theory that mitochondria and chloroplasts were once free living bacteria that got absorbed by a larger cell (ancestoral prokaryorte— and instead of being digested, they became permanent residents

• Contains phosphate group and glycerol

• Polar

• Hydrophilic: Interacts with water

is the tail hydrophobic or hydrophillic

• Contains a saturated and unsaturated fatty acid

• Non-polar

• Hydrophobic: repels water

cholestrol

Regulates membrane fluidity in response to temperature changes.

glycolipids

id

Carbohydrate attached to a phospholipid;

facilitates cell-to-cell recognition.

4 types of proteins in membrane

• transport

• receptor

• glycoproteins

• enzymatic

what type?

transport protein

describe transport protein

Moves large, polar, or charged substances from one side of the membrane to the other.

what type?

receptor protein

describe receptor protein?

Embedded in the membrane receiving external signals for internal response

what type?

glycoprotein

describe glycoproteins

Carbohydrates attached to a protein; allow cross linking of cells which gives tissues strength.

what type?

enzymatic protein

enzymatic protein

Protein which carries out metabolic reactions.

importance of cell transport

• Transport of waste out of the cell

• Helps maintain pH and salt balance.

• Transport signal proteins out of the cell

• Helps cells communicate, like in the nervous system.

• Absorption of nutrients into the cell.

• Allow oxygen into the cell for respiration

• Allows for CO2 to leave cells

• Can assist in apoptosis in infected cells.

• ETC.

passive transport

Net movement of molecules with the concentration gradient until the system reaches dynamic equilibrium with NO energy used.

HIGH TO LOW

active transport

Net movement of molecules against the concentration gradient. System will not reach dynamic equilibrium

Requiring energy!

facilatated diffusion

Net movement of large, polar, or charged molecules with the concentration gradient that requires the use of a transport protein to occur.

simple diffusion

osmosis low

high water concen to low water concen

passive transport examples

1. facilitated diffusion

2. Osmosis

3. simple diffusion

active transport

Transport of a substance from an area of low

concentration to an area of high concentration using ATP (cell energy).

This is referred to as moving against the concentration gradient.

LOW TO HIGH

active transport

• endocytosis

• exocytosis

• 

endocytosis

. Phagocytosis ("cell eating") 🍽

• Cell engulfs large solid particles

• Examples: white blood cells eating bacteria, amoeba eating food

• Forms a phagosome (large vesicle)

2. Pinocytosis ("cell drinking") 💧

• Cell engulfs liquid and dissolved particles

• Happens continuously in most cells

• Forms small vesicles

3. Receptor-Mediated Endocytosis 🎯

• Most specific type

• Receptors on cell surface bind to specific molecules

• Only takes in what the receptors recognize

• Example: cells taking in cholesterol (LDL)

exocytosis

• Neurotransmitters released from neurons into synapse

• Hormones secreted into bloodstream

• Digestive enzymes released from pancreas

• Mucus secreted from cells

• Waste removal from cell

membrane potential

separation of charge across the membrane creates a membrane potential

osmoregulation

maintains water balance and allows organisms to control their internal solute compositon/ water potential

freshqater fish

• Live in hypotonic environment (water has fewer solutes than fish body)

• Water constantly flows IN

• Solution: kidneys work overtime to excrete lots of dilute urine

• Actively take in salts through gills

saltwater fish

• ive in hypertonic environment (water has MORE solutes than fish body)

• Water constantly flows OUT — risk of dehydration

• Solution: drink lots of seawater, excrete small amounts of concentrated urine

• Actively pump excess salt out through gills

tonicity stuff

make sure to predict and udnerstand