Cell Structure

1. Composed of a phospholipid bi-layer. Permeable to polar materials, non-polar materials must pass through channels.

Plasma Membrane:

Construction of Cell Membrane

http://www.wisc-online.com/Objects/ViewObject.aspx?ID=AP1101

Cellular Transport

Osmosis- diffusion of water across a selectively permeable membrane.

Review: diffusion is the movement of materials from a area of high concentration to an area of low concentration.

Concentration gradient: If 2 solutions are separated by a semi permeable membrane the water will flow to the side where water concentration is the lowest.

OSMOSIS

Hypertonic Isotonic Hypotonic

Cells in Hypotonic Solutions- swell

Cells in hypertonic solutions-shrink

Three forms:◦Diffusion◦Facilitated diffusion (using a pore protein

like water)◦Osmosis (diffusion of water)

Passive Transport- no energy

high

low

Weeee!!!

Three Forms:◦ Protein Pumps- Channel proteins◦ Exocytosis- things exit out of cell◦ Endocytosis- things taken into the cell

Active Transport- needs energy

high

low

This is gonna be

hard work!!

Exocytosis- expulsion or sercretion of large molecules. Ex. Waste

Endocytosis- Cell surrounds and takes in material from environment.

Transportation of Large Particles

Leader of the cell b/c it contains the directions to make proteins

EVERY part of the cell depends on protein Covered by a nuclear envelope or

membrane separating the nucleus from the cytoplasm.\

Nucleus and Cell Control

Master set of directions for making proteins is contained in CHROMATIN- strands of the genetic material DNA.

Cell Control Cont…

Nucleolus organelle within the nucleus that makes ribosomes.

Ribosomes Site where cells produce proteins according to DNA directions

ribosomes

Cell control cont…

For proteins to be made, ribosomes must leave the nucleus and enter the cytoplasm where the DNA blueprints are turned into protein.

CYTOPLASMClear gelatinous fluid within the cell. Ribosomes go through the nuclear envelope into the cytoplasm

Cell control cont…

1. ENDOPLASMIC RETICULUM- Site of cellular chemical reactions (metabolism)

Smooth ER- has no ribosomes and looks looks smooth.

Rough ER- studded with ribosomes and and and is therefore the site of protein synthesis.

ASSEMBLY, TRANSPORT AND STORAGE.

Golgi Apparatus: “POST OFFICE” Flattened stack of tubular membranes that packs sorts and delivers proteins to their appropriate destinations with VESICLES.

Assembly storage and transport cont…

Membrane bound compartments for temporary storage of enzymes or materials needed by the cell. Usually water in a plant

Vacuoles and storage

Lysosomes- organelles containing digestive enzymes (lyse= to break). Breaks down worn out organelles, food particles, viruses, bacteria. Membrane important to protect cell from being digested.

Can fuse with vacuole and digest its contents.

Lysosomes and Recycling

Detoxify harmful substances that enter the cell.

Seen especially in kidney and liver Contain peroxidase and catalase (some

chemical reactions in the body create hydrogen peroxide which is toxic to cells. Peroxidase breaks this down.

Peroxisomes

EVERYTHING we have talked about within the cell needs energy. In humans this is provided by

◦ MITOCHONDRIA

ENERGY TRANSFORMERS

Membrane bound organelles in plants and animals that transform energy for the cell.

Energy is stored in the bonds of other molecules that cell organelles can easily access as needed.

Mitochondria- all cells

Outer membrane Inner membrane highly folded to increase

surface area for storage of energy molecules.

Muscle cells have up to 2000 mitochodria in one cell!

Mitochondria cont…

Cytoskeleton- framework for the cell. Initially thought that the organelles floated in cytoplasm.

Network of 1.Microtubules-thin Hallow cylinders madeOf protein.2. Microfilaments- smallSolid protein fibers

Organelles for SUPPORT and LOCOMOTION.

Forms a SCAFFOLD that◦ Maintains cell shape◦ Anchors and supports organelles◦ Highway system for organelles

Cytoskeleton cont…

Centrioles: Cell organelles found in Animals and most

protists. Occur in pairs. Made of microtubules Important to cell division

Locomotion

Made of microtubules that aide the cell in locomotion and feeding. Major means of locomotion in unicellular organisms.

Cilia- short, hair-like◦ Rowboat motion

Flagella- long whip-like movement

Cilia and Flagella

Desmosomes◦ Fibrous

connections between cells

Cell Connections

Gap junctions- connections through a channel.

Cell connections cont…

Tight Junctions- cells tied together

Cell connections cont…

Cell structure is related to its function.

1. If the liver stores and releases glycogen (glucose) what type of organelles would it have a lot of?

2. What organelle would a muscle need a great deal of?

3. The adrenal gland produces hormones (which are made of protein and lipids). What organelle/s would it have a lot of?

Structure and Function