Unit 5

Cell Structure and Function

Chapter 7

The Cell Theory

• All living things are composed of cells

• Basic units of structure and function in living things

• Cells are produced from existing cells

Categories of Cells

• Type 1 – Prokaryotes• No Nucleus• Example - Bacteria

Categories of Cells

• Type 2 – Eukaryotes• Has a Nucleus• Example – Plant,

Animal, fungi

Types of Cells in the Human Body

• •

• •

Two Types of Eukaryotes – Animal and Plant Cell

Cell Structures in common

Cell Membrane Nucleus Ribosome

Endoplasmic

Reticulum

Vacuoles Mitochondria

Nucleus

• Controls most of cells processes

• Contains genetic information-DNA

• Chromosomes inside nucleus are the threadlike structures containing genetic information

Ribosomes

• Makes proteins for cell

• Instructions come from the nucleus

Endoplasmic Reticulum

• Synthesizing, packaging and transporting of proteins

• Two types – rough ER and smooth ER

• Network of membranes

Golgi Apparatus

• Packaging system• Takes small molecules

and makes larger ones then stores them

• Proteins

Vacuoles

• Storage areas for water, salt, proteins, carbohydrates

Mitochondria

• Synthesis and release of energy

• Powerhouse of cell

Cell Membrane

• Allows movement of materials in and out of cell

Cell Wall (Plant Only)

• Provides support, protection and structure for plant cell

Chloroplast (Plant Only)

• Site of photosynthesis

Cell Membrane

• Regulates what enters and exits the cell

• Provides protection and support

• Semi-permeable – allows small substances through and keeps larger substances out

• Made of lipids and proteins

Cell Membrane

Types of Movement through the Cell Membrane

• Active Transport • Passive Transport

Passive Transport

• Diffusion – substance moving from an area of high concentration to an area of low concentration

• Concentration means the amount substance in a given area

• No energy required

Passive Transport

• Osmosis – diffusion of water through the cell membrane

Effects of Osmosis

• Water will move in the direction where there is a high concentration of solute (low concentration of water )

• Salt Sucks – Salt is a solute, when it is concentrated inside or outside the cell, it will draw the water in its direction. This is also why you get thirsty after eating something salty.

Isotonic solution

• If the concentration of solute (salt) is equal on both sides, the water will move back in forth but it won't have any result on the overall amount of water on either side.

"ISO" means the same

Hypotonic Solution

The word "HYPO" means less, in this case there are less solute (salt) molecules outside the cell, since salt sucks, water will move into the cell.

The cell will gain water and grow larger. In plant cells, the central vacuoles will fill and the plant becomes stiff and rigid, the cell wall keeps the plant from bursting

In animal cells, the cell may be in danger of bursting, organelles called CONTRACTILE VACUOLES will pump water out of the cell to prevent this.

Hypertonic Solution

• The word "HYPER" means more, in this case there are more solute (salt) molecules outside the cell, which causes the water to be sucked in that direction.

• In plant cells, the central vacuole loses water and the cells shrink, causing wilting.

• In animal cells, the cells also shrink.• In both cases, the cell may die.

Effects of Osmosis

Active Transport

Movement through a membrane that requires energy

Diversity of Cellular Life

Cell Specialization – when a group of cells work together to perform a specific job

Levels of Organization