Ch. 8 Cell Structure & Function

Lesson 1: What Do Cells Do?

CellsMain Idea: All living things are made of cells. To

stay alive and healthy, cells need food and water. They also need a way to get rid of waste.

Plant Cells and Animal Cells• A single cell is the smallest structure that carries

out activities necessary for life.• A cell is like a tiny factory: different parts of the

factory produce or control different things.1. gets food or water2. keeps cell clean3. in charge of reproduction

•Like parts of a factory, all parts must work together to run smoothly.•An organism can’t survive without cells doing their work.•Animal and plant cells look different, but share many similar features.•Common features:

1. cell membrane2. nucleus3. cytoplasm

Cell membrane•Outer covering of cell•Water and food enter through it•Wastes leave through it

• Plant cells have extra structure called cell wall which adds more support to plant cell.

Nucleus• Control center of cell• Carries information for reproduction• Directs all cell activities

Cytoplasm• Gel-like material that surrounds all parts of cell

within membrane• Contains nucleus and cells’ organelles

•Organelle-small structure that has certain job1. mitochondria2. vacuoles3. nucleus4. cell membrane5. golgi bodies and endoplasmic

reticulum

•Chloroplast-special organelle that uses energy of sunlight combined with water and carbon dioxide to make food for cell

Cell Transportation•Cell membrane holds cell matter inside, but allows water, gasses, and wastes to pass through.

• In passive transport, matter moves into or out of cell

without cell using any energy• Simplest kind of passive transport-diffusion• Diffusion:

1. Spreads substances through gas or liquid (can smell dinner across room b/c food molecules diffuse through air)

2. Transports many gases into and out of cells3. Substances diffuse from areas of high

concentration to areas of low concentration

• Special form of diffusion-osmosis

Osmosis:•Diffusion of water across membrane•Membrane stops many substances that are dissolved•Often keeps water inside cells•Sometimes a cell needs to move materials opposite to the way diffusion would move them.•In active transport, substances move from areas with less matter to areas with more matter•Cell must use energy to do this.•Large proteins in cell membrane help move materials in and out.•Protein acts as tunnels that allow certain materials to pass.

•Scientists study these proteins for clues to how cells operate.

Using Energy•All living things need energy to survive.•Plants use chloroplasts to make food by using energy of sunlight, water, and carbon dioxide•Process takes place in chloroplasts and depends on green pigment called chlorophyll.•Chlorophyll captures energy from sunlight.•Photosynthesis: 1. series of chemical reactions join water from ground with carbon dioxide from air.

2. By products are oxygen, which plant releases into air, and a molecule called glucose.

•Glucose 1. High energy material that is classified as sugar 2. Plants and animals use sugar for food. 3. Plant and animal cells have organelles called mitochondria. 4. Mitochondria-break down sugars so cells can use sugars as energy

•Mitochondria 1. perform cell respiration (reverse reaction to photosynthesis) 2. Break down sugars to make energy

3. process combines glucose with oxygen to form water and carbon dioxide 4. lot of energy released in process 5. store energy in molecule called ATP which is released during cell respiration 6. ATP acts like battery-cell can draw from ATP whenever it needs to use energyCell Division•Body is made of trillions of cells•Began as one single cell•Cells copy themselves in process known as cell division•New organisms begin when cells from two parents combine to form fertilized egg.•Soon the single cell divides into 2 cells.

•Two cells divide into 4 cells•Four cells divide into 8 cells•Sometimes cells divide within hours allowing organism to grow very quickly.•As cells divide, they differentiate (become different from one another)•Early on, cells organize themselves into 3 groups called germ layers: 1. form the skin and nerves 2. becomes the lining of the digestive tract 3. produces all other body parts

•Bacteria and other single-celled organisms can copy themselves which results in new individuals.•When conditions favor division, a bacteria colony can double very quickly.

That’s all folks!