Biology Unit 4 Cells IHS Skavaril

Cell membrane

Controls what goes in/out of the cell. Made up of phospholipids and membrane proteins

Membrane protein

Allows large polar molecules in/out

Cell wall

Gives structure and support

ONLY IN PLANT CELLS

Cytoskeleton

Inside structure and support

Lysosome

Destroys unknown material

Vacuoles

Storage (e.g. water, protein, lipids, etc.)

Nucleus

Stores DNA

Nucleolus

Condensed area of DNA

DNA

Instructions

Mitochondria

Power converter; convert glucose to usable energy (ATP)

Chloroplast

Converts sunlight into glucose

ONLY IN PLANT CELLS

Smooth endoplasmic reticulum (Smooth ER)

Makes lipids

Rough endoplasmic reticulum (Rough ER)

Makes proteins

Ribosome

Machine that makes proteins

Golgi Apparatus

Packing and shipping center for lipids and proteins

Vesicles

The movers

Central vacuole

Stores water

ONLY IN PLANT CELLS

Centriole

Helps with reproduction

ONLY IN ANIMAL CELLS

The 3 cell theories

1. Every living thing is made of cells

2. Cell is the basic unit of life

3. All cells come from other cells

Organelles

Specialized part of a cell with a specific job

Eukaryotic cell

• Bigger

• More complex

• Has nucleus

• DNA

• E.g. plants

Prokaryotic cell

• Smaller

• Less complex

• Does not have nucleus

• DNA

• E.g. bacteria

Phospholipid

Two-sided; hydrophilic side and hydrophobic side

Phospholipid bilayer

Hydrophobic on the side, hydrophilic in the inside

What do membrane proteins do

Helps move large/polar molecules across the cell membrane

How are cell membranes selective permeable

Only let certain molecules through (small/nonpolar molecules)

Passive transport

Does not require any energy (ATP). Happens through diffusion, facilitated diffusion, or osmosis. Solutes flow from high → low concentrations

Active transport

Requires energy (ATP). Happens through protein pumps, endocytosis, or exocytosis. Solutes flow from low → high concentrations

Diffusion

Passive transport: Process where a molecule moves across the membrane without an input of energy

Facilitated diffusion

Passive transport: Requires membrane proteins for molecules to move across the cell membrane

Osmosis

Passive transport: The diffusion of water across a membrane via aquaporins

Aquaporin

A pore that water can diffuse though; a type of membrane protein

Endocytosis

Active transport: Process where molecules are taken into the cell through a vesicle

Exocytosis

Active transport: Process where molecules are put out of the cell through a vesicle

Protein pumps

Active transport: Uses energy, in the form of ATP, to move molecules across the membrane against concentration

Transport

Describes which molecules move

Tonicity

Describes the direction that molecules move

Concentration

Amount of molecules in an area

Solutes

Molecules dissolved in water; things being dissolved

Solution

Water with dissolved molecules; things being dissolved + water

Hypertonic

Higher solute concentration

Hypotonic

Lower solute concentration

Isotonic

Equal solute concentration; equal movement in and out of cell

Concentration gradient

Two solutions separated by a membrane

Cytolysis

So much water enters the cell that the cell bursts

Plasmolysis

Water leaves the cell so the cell shrinks

Flow of water

Hypotonic → Hypertonic

High → Low

Flow of solute

Hypertonic → Hypotonic

High → Low

What is used to maintain homeostasis

Organs

You decide to buy a new fish for your freshwater aquarium. When you introduce the fish into your tank, the cells of the fish swell up and the fish dies. You later learn that it was a fish from the ocean.

Based on what you know of tonicity, why did the fish swell and die?

The fish was hypertonic compared to the solution, so the water rushed into the fish

Scientists used to think that these wrinkles form when your skin swells (get bigger) with water. Now data shows that the wrinkles are caused by constricting blood vessels. Why did scientists used to think that hands swell and form wrinkles when exposed to water for too long?

The skin cells are hypertonic compared to the water, hence the swelling as water flows into the cells. Scientists must’ve seen this phenomenon and concluded that these two were directly related.

Ocean water is very dangerous for a person to drink. The average salinity (tonicity of salt) of ocean water is 3.5%, the average human body salinity is around 0.09%. What happens when a human drinks salt water?

The human body is hypotonic compared to the ocean water solution, so the water in the human body would leave and make the person dehydrated.

Nutrients and water are delivered to the cells in your body through your blood vessels. Blood vessels are also passageways for red blood cells to deliver oxygen to your cells. Healthy red blood cells are capable of carrying 4 molecules of oxygen at a time, but this capacity is DEPENDENT on their shape. If a person becomes severely dehydrated there is less water in the blood vessels that carry red blood cells.

a. What will happen to red blood cells when a person becomes severely dehydrated?

b. Why will this occur? Use tonicity vocabulary to explain.

c. Are the red blood cells likely to be effective at carrying oxygen under these conditions?

d. What is likely to happen to a severely dehydrated person that does not restore water to their blood vessels?

e. What happens to a blood vessel and red blood cells when a person drinks too much water?

a. The red blood cells would shrink

b. Because there is less water in the blood vessels, the water in the RBC will flow out and into the vessels as the RBC is now hypotonic and the blood vessels are hypertonic

c. No. The loss of water will make it change shape, altering its function or its ability to function properly

d. They die as there is a lack of oxygen being carried throughout their body

e. The RBC are now hypertonic and the blood vessels are hypotonic, so the water will rush into the RBCs and cause them to burst

Levels of organization

Cell → tissue → organ → organ system → organism

How are proteins made

Nucleus (stores the DNA/instructions), ribosomes (builds the proteins), rough ER (folds/modifies proteins for export/membranes), Golgi (packages and ships proteins), vesicles (movers), mitochondria (provides energy)