Chapter 7 Cells and Organelles

Background Every living thing is made of cells Robert Hooke coined the term “cells” Antonie van Leeuwenhoek discovered the first living cell

The Cell Theory states that: All organisms are composed of one or more cells. The cell is the basic unit of organization in all organisms. All cells come from pre-existing cells

Levels of organization Smallest living unit is the cell Cells Tissues Organs Organ System

Two types of cells Types of cells Prokaryotes – simple cells, bacteria Eukaryotes – complex cells, animal and plant We will go over move differences later…

Inside the cell there are smaller parts called organelles Organelle means little organ

Plasma Membrane The plasma membrane, aka the cell membrane, surrounds the cell It is present in all cells Function – controls what enters and leaves the cell Selectively permeable – selects what moves through it

Plasma membrane Structure Phospholipid bilayer Proteins Carbohydrates

Cell Wall Surrounds some cells Though and ridged Made of cellulose Plant cells, fungi cells, and bacteria cells Though and ridged Made of cellulose

Nucleus Controls everything in the cell Reproduction, movement, eating Only present in eukaryotic cells Contains all genetic information

Surrounding the nucleus is the nuclear envelope Inside the nucleus is the nucleolus The nucleolus produces an organelle called the ribosomes

Ribosome Ribosomes are the site of protein synthesis Found all over the cell

Endoplasmic Reticulum Two types: smooth and rough Smooth – stores lipids Rough – after the ribosomes make proteins the rough ER packages them in vesicles to move around, or out of, the cell Rough because it is covered in ribosomes

Golgi Apparatus Modifies proteins before they are sent out of the cell

Production of Proteins Each organelle has a role to play in the production of proteins

Vacuole Main function is storage In both plant and animal cells, but they are much larger in plant cells

Mitochondria Produces energy for the cell Does this through a process called cellular respiration Many folds to increase surface area Why?

Chloroplast Produce sugar, or food, by using light energy This process is celled photosynthesis Found in plant cells and protist cells

Lysosome The lysosomes job is to digest things that are no longer needed by the cell Contain special enzymes to do this

Different types of cells

Animal v. Plant Cells

Different types of cells

Stem cells Eukaryotic organisms begin as a mass of cells Each cell has the same DNA so how do we end up with hundreds of cell types? It has to do with the DNA!

Stem Cells Cell differentiation is when these cells become different. When this happens only specific parts of the DNA are activated. the parts of the DNA that are activated determine the function and specialized structure of a cell. Once a cell is differentiated it cannot be reversed. So what does this have to do with stem cells?

Stem Cells Stem cells have not differentiated yet They have the ability to become any cell! Embryonic stem cells – found in the embryo Adult stems cells – found in adult living organisms (example – bone marrow) Both types have potential to be come specialized cells Why is this important?? How can it be useful??