The Cell & Cell Processes

I. Factoids

A. You have approximately 7.5 TRILLION cells that make you up.

B. 200 different types of cells work together and form the tissues that make up our organs.

Remember from your reading that cells have functions.

Cell theory• Cells are the basic unit of life.

• Everything that happens to you happens on a cellular level.

• Cancer? Cellular.

• Disease? Cellular.

• Poison? Cellular.

• Cells look & perform (structure/function) differently based on their purpose in the cell.

• To do their “jobs” they come in different sizes & shapes and have different numbers of organelles.

But we study this guy b/c• All cells have

the same basic parts.

• 1. PM

• 2. cytoplasm

• 3. nucleus

• And allows us to understand the purpose of any cell if we know the function of the organelles

Organelles

• “tiny organ”-awe

• You should know the names and functions of each organelle for your quiz next class!

I’m Cute and Tiny

Nucleus

• Contains nucleolus & DNA.

– DNA (genetic material) controls cell processes

Nucleus

DNANucleolus

Nuclear envelope

• Membrane surrounding / protecting nucleus

Nucleolus

• Makes Ribosomes

Ribosome

• Assembles (makes/synthesizes) proteins

mRNA

tRNA

Becomes a protein

Smooth Endoplasmic Reticulum-I’m important!

• No ribosomes

• Makes lipids, breaks down toxins, stores calcium in muscle cells

Rough Endoplasmic Reticulum

• Has ribosomes

• Packages proteins in pieces of its own membrane

Mitochondria- I’m really important! • Transforms food

molecules into energy for cell

• Cellular respiration- the conversion of “food” molecules into ATP. Requires oxygen creates carbon dioxide(why we breathe)

Golgi Apparatus

• Receives, modifies & packages newly made proteins

Vacuole (animal)

• Stores food & waste molecules

• Many small

Food Vacuole

Waste Vacuole

Lysosome

• Contains enzymes that break down molecules

Cytoskeleton

• Network of protein fibers that give cell structure & helps cells move.

Cytoplasm

• Liquid material that organelles reside in.

• Cellular metabolism occurs here.

Plasma (Cell) MembraneThe plasma (cell)

membrane is semi (selectively) permeable. This means that it only allows certain materials in/out of the cell.

This is important for maintaining homeostasis inside our cells

outside membrane inside

PM proteins- make the PM special!• Transport- pump material across

• Enzymatic- metabolic pathways

• Receptors- picks up signals (hormones) that activate chemical changes

• Intercellular- joins 2 cells

• Recognition- ID tags (glycoproteins) for “Self” recognition***

• Attachment- hold cell in place OR help cell move

Cells stick together…sort of…• Tight junctions- stop other cells from squeezing

in-between cells that are next to each other. Like a fence would stop you from using a gangway between houses.

• Desmosomes- prevent cells from separating from each other. Like buttons on a shirt stop the shirt sides from opening. In this case the shirt never opens.

• Gap Junctions: Passing chemicals between cells. Like a drive through window at a fast food restaurant.

• Got a better simile? Lay it on me.

The space in-between• All the fluid in the cell is the cytoplasm.

• All the fluid outside the cell is the extracellular fluid and it’s called the Interstitial fluid.

• Comes from blood

• Mostly water with stuff the cell needs dissolved in it and stuff the cell has released (waste).

Getting stuff in and out WP 3.2

Membrane transport

A. Solution: mixture of 2 or more components

1. Ex: seawater

B. Solvent: present in the largest amount, what something is dissolving in.

1. Ex: water

C. Solute: what dissolves into the solvent

1. Ex: salt

Membrane transport

D. Cytoplasm (Intracellular fluid): fluid in the cell w/ gasses, salts & nutrients

E. Interstitial fluid: fluid that bathes the outside of the cell.

1. Has thousands of ingredients (sugars, amino acids, fats, vitamins, hormones, salts, waste products)

Membrane transport

Passive transport

1. Diffusion: substance moves from higher to lower concentration to balance

a. The difference between the 2 concentrations is the concentration gradient

b. http://www.youtube.com/watch?v=VY0mZUDvbH4

diffusion

1. For diffusion to work there must be a difference in the solute concentration across space or across a membrane called a concentration gradient.

2.) So, we can say that molecules move down their concentration gradients from high concentration to low concentration.

Remember: our cells have watery internal & external environments. Diffusion is how solute molecules move in/out of our cells. The same principle also applies to water molecules.

III. Osmosis

– the diffusion of water across a semi-permeable membrane from an area of high water concentration to an area of low water concentration.

High water/ low salt

Low water/ High salt

Water moves towards the low concentration of water

A cell loses water by osmosis when the area outside of the cell has less water.

a. Ex: Cells shrink in highly salty water

“Normal” Interstitial Fluid, Homeostasis between water and salt

Low water / High salt in Interstitial Fluid

Water moves out of cell and cell shrinks!

Cells will gain water when the area outside of the cell has more water.a. Ex: Cells bloat / explode

“Normal” Interstitial Fluid Interstitial Fluid too watery

Water moves into cell & cell bloats

• This is what happened to the woman that drank too much water. Her interstitial fluid became too watery.

Passive Transport: no energy required!

Osmosis/Diffusion Facilitated Diffusion

High to low

Facilitated Diffusion – cell does not use energy, but molecules use protein channels in the plasma membrane to enter the cell.

Filtration:

Filtration: pressure (from heart beating) is applied to force water and it’s dissolved materials across a membrane.

Ex: Kidneys

Diagram of simple filtration: oversize particles in the feed cannot pass through the lattice structure of the filter, while fluid and small particles pass through, becoming filtrate.

Active transport

Active transport= needs energy

a. Cells must use energy to move molecules from areas of low concentration to areas of high concentration.

Low to High!

Diffusion, osmosis & facilitated diffusion: With the concentration gradient = No Energy

Active Transport: Againstthe concentration gradient = Uses Energy!

Endocytosisa. Intake of food (or water) when the quantity is too large to

pass through the membrane.

b. Membrane surrounds and pulls substance in.

i.Phagocytosis-

solid material

http://www.youtube.com/watch?v=pvOz4V699gk (mute)

Exocytosis

Transport of substances outside of the cell.

• Apply!

• https://www.youtube.com/watch?v=l79FuGuk1qE&feature=youtube_gdata

• Big bugs?

• Review

• https://www.youtube.com/watch?v=dPKvHrD1eS4

• Crash course