Cells Unit 3 chapter 7

Cells - Basic unit of structure and function of living things.

 Organelles - Tiny organs within cells.

 Cell Theory

1) All living things are made up of cells.

2) Cells are the basic units of structure and function in living things.

3) Living cells come only from other living cells.

Scientists -

Robert Hooke - Observe room-like structures he called “cells” 1665.

Anton Van Leenwenhoek - Made simple microscope-saw living cells.

3 scientists whose work led to cell theory.

Mathias Schleiden - Botanist

Theodore Schwann - Botanist

Rudolph Virchow - Physician

 Exceptions to cell theory - Chloroplasts and Mitochondria have their own DNA

Virus cannot reproduce on their own but must invade a living cell. Considered my some scientists to be nonliving

2 Types of cells

a. Prokaryotes – Smaller and simpler cells – Have membrane and cytoplasm but no nucleus. Example Bacteria, Kingdom moneran.

b. Eukaryotes – Larger more complex – Have nuclei and many other organelles


A.  Nucleic acids - Large complex molecules, found in nucleus, store the information that helps a cell make the substances it needs.

Two types of Nucleic Acids

1.  DNA - Deoxyribonucleic acid.  Stores information needed to build proteins.

2.  RNA - Ribonucleic acid.  “Reads” the DNA messages and guides the protein-making process. 

Chromatin - threads of DNA in nucleus, called Chromosomes when Wound up.  Carry Traits.

Nucleolus – Where ribosome’s are made.

Nuclear Envelope (Membrane) - Separates the nucleus from the rest of the cell. Has holes in it called pores which allow RNA and material to move in and out.

Cell membrane - Thin, flexible, envelope that surrounds the cell - controls movement of material into and out of the cell.

Cell wall - only in plant cells, made of cellulose.  Give support.

Nucleus – large structure contains cells genetic material (RNA DNA) controls cells activity

 Cytoplasm – Material inside the cell membrane but outside the nucleus.

 Cytoskeleton – a network of protein filaments that help the cell maintain shape and sometimes move. Made of Microtubules and microfilaments

 Ribosomes - small made of RNA produce proteins based on instructions from the nucleus

 Endoplasmic Reticulum – maze like passageway – newly made proteins may be modified here cell membranes assembled here

Rough ER has many ribosomes attached to it.

 Golgi Apparatus – Stack of membranes like folded garbage bags – here enzymes attach carbohydrates and lipids to proteins which then move to their final destination

 Lysosomes - Small round packets of digestive enzymes.

 Vacuoles - large round sacs.  (Storage tanks) Plant cells generally have one large vacuole which stores water.

 Chloroplasts - Only in plant cells.  Contain chlorophyll use energy of the sun to form glucose (high energy compound) in photosynthesis.

 Mitochondria - (rod-shaped) - Supply energy (the powerhouse of the cell).  Break down glucose and store energy in complex molecule. ATP

* Chloroplasts and Mitochondria have their own DNA

 Centrioles – Take part in cell division

 Cells are like factories labor is divided among parts each with a special purpose.

  Organization of Living Things

Within a cell or within an organism, the work of life processes is divided among different parts.  This is called Division of Labor.

Five basic levels of organization from simplest to most complex are:

1 - Cells

2 - Tissues

3 - Organs

4 - Organ Systems

5 - Organisms

1 - Cells - Basic unit of structure and function in all living things, from one-celled organisms to us.

2 - Tissues - Cells that are similar in structure and function, joined or working together.

ex.  muscle tissue                        Bone tissue

3 - Organs - Groups of different tissues working together.

ex.  biceps,                        Heart                        Femur

4 - Organ Systems - A Group of Organs that work together to perform a certain function.

ex.  muscular system                        skeletal system.

5 - Organisms - An entire living thing that carries out all the basic functions of life.

ex.  human, bacterium, pine tree.

Surface area to volume – some cell parts and body parts are composed of folds to increase the surface area for absorption or diffusion.