Cell Structure and

Function

The Discovery of the Cell

• Robert Hooke – first to see and identify cork “cells” using a microscope.

7-1www.nerdscience.com

The Cell TheoryCell Theory:1. All living things are made of one

or more cells.2. Cells are the smallest unit of

life.3. New cells are produced from

pre-existing cells.

Schleiden Schwann

Virchow

7-1www.nerdscience.com

Basic Cell Substances• The main ingredient of any cell is water.

• The structure of a water molecule makes it ideal for dissolving many other substances

Macromolecules• Macromolecules form when many small

molecules join

• The 4 types of macromolecules are:1. Nucleic acids-

• form when long chains of nucleotides join.• Important because they contain genetic

information• Ex: DNA and RNA

Macromolecules4. Proteins-

• Necessary for nearly everything cells do• Made up of long chains of molecules called

amino acids.• Some help break down nutrient in food

3. Lipids- • large molecule that does not dissolve in water• Store energy• Plays an important role as protective barriers

in cells (membranes)

Macromolecules4. Carbohydrates-

• Made up of one or more sugar molecules• Store energy• Provide structural support• Used for communication between cells

Prokaryotes and Eukaryotes

Cells can be grouped into 2 types:1. Prokaryotes – cells that do not

contain nuclei. o Ex: (Bacteria)

2. Eukaryotes – cells that contain nuclei and have membrane-surrounded components called organelles which have specialized functionso Ex: plants, animals, fungi,

protist

Eukaryotic Cell Structure

• Organelles – structures in a cell that act like “little organs.”

• Cytoplasm – the jelly-like fluid where the organelles “float.”o It contains salts and other molecules

The Nucleus• Nucleus – large membrane-enclosed structure that

contains the cell’s genetic information and directs cell activities

o Nuclear Envelope – membrane that surrounds the nucleus.

Nuclear Envelope

Mitochondria• Mitochondria – converts chemical energy stored in

food into energy(ATP).o “Powerhouse of the Cell!”o Converts glucose and oxygen into ATP, Carbon

Dioxide (CO2) and Water (Cellular Respiration)

• ATP- the fuel for cellular processes such as growth, cell division, and material transport

www.nerdscience.com

Mitochondria

Mitochondria

Ribosomes• Ribosomes – Make Proteins!

o Found in a cells cytoplasm or attached to the endoplasmic reticulum (E.R)

Ribosome

Endoplasmic Reticulum (ER)

• Endoplasmic reticulum –transports proteins to the Golgi apparatus and breaks down toxic material.oRough ER – has ribosomesoSmooth ER – no ribosomes

Endoplasmic Reticulum (ER)Rough ER

Smooth ER

Golgi ApparatusGolgi Apparatus (Golgi bodies)- prepares proteins and packages them into ball-like structures called vesicles

Golgi Apparatus

LysosomesLysosomes – small organelles filled with enzymes that help recycle cellular components

Vacuoles• Vacuoles – store food, water, and waste

materialoAnimal cells have small vacuoleso Plant cells have large Central VacuolesVacuoles

ChloroplastsChloroplasts – organelles that capture energy from sunlight and convert it into chemical energy. (Photosynthesis)

o Found only in plants.

Chloroplast

CytoskeletonCytoskeleton – made of a network of threadlike proteins that are jointed to form a framework inside a cell.

• helps cell to maintain shape, move, and move organelles.

Cell BoundariesCell membrane – thin, flexible membrane that surrounds the cell and protects the inside of a cell from the environment outside.• Controls what enters and leaves the cell.• Made of phospholipids (2 layers) and proteins.

Two layers!

Cell BoundariesCell wall – rigid layer around the membrane that provides structure and support.• found only in bacteria, fungi and plants.

Cell AppendagesCell appendages are often used for movement.

• Flagella- long, tail- like appendage that whip back and forth and move a cell.

• Cilia- short hair like structures that can move a cell or move molecules away from a cell.

Moving Cellular Material

• The exchange of materials between as cell and its environment takes place at the cell membrane.

• A cell membrane is semipermeable- it allows only certain substance to enter or leave a cell

Passive Transport

1. Passive transport – the movement of substances through a cell membrane without using the cell’s energy

a. Diffusion – movement of particles from an area of high to low concentration.• Diffusion continues until

the concentration of a substance is the same on both sides of a membrane.

b. Osmosis – the diffusion of water through a membrane.

Osmosis Practice

Cell

90% H2O10% NaCl

90% H2O10% NaCl

Concentrations areequal, so no netmovement of water!

7-3www.nerdscience.com

Osmosis Practice

Cell

90% H2O10% NaCl

80% H2O20% NaCl

Concentration ofwater is greater inthe cell than out, sowater will move out!

www.nerdscience.comwww.nerdscience.com

Osmosis Practice

Cell

80% H2O20% NaCl

90% H2O10% NaCl

Concentration ofwater is greateroutside the cell than in, so water will move In!

7-3www.nerdscience.com

Active Transport2. Active Transport- The movement of materials across a cell membrane with the use of energy

a. Exocytosis – a cell’s vesicles releases their contents outside of the cell.

b. Endocytosis – the cell surrounds a large particle and brings it into the cell

• Moves substances from areas of low concentration to areas oh high concentration

Cell Size and Transport

• For a cell to survive, its surface area must be large compared to its volume.

• As a cell grows, its volume increases faster than its surface area

Cells & Energy

CELLULAR RESPIRATION

All living things need energy to survive

Cellular Respiration – converts the energy in food molecules into a usable form of energy called ATP

CELLULAR RESPIRATIONStep 1: Glycolysis- occurs in the cytoplasm of all cells

• Glucose is broken down into smaller molecules

Step 2: Occurs in the mitochondria of Eukaryotic cells and requires oxygen

• Small molecules made during glycolysis are broken down

• Large amounts of usable energy called ATP are produced

• Water and Carbon Dioxide is given off

CELLULAR RESPIRATION

7-3www.nerdscience.com

FERMENTATION• Eukaryotic and prokaryotic cells use fermentation to obtain

energy from foods when oxygen levels are low.

• It occurs in the cell’s cytoplasm

Lactic- acid fermentation- Occurs in muscles

C6H1206 ATP + Lactic Acid (Glucose) (energy)

Some types of bacteria and yeasts make ATP during alcohol fermentation.

C6H1206 ATP + Alcohol + CO2 (Glucose) (energy)

PHOTOSYNTHESIS• Plants and some unicellular organisms obtain energy

from light (radiant energy)

• Photosynthesis is a series of chemical reactions that converts light energy into chemical energy (Glucose)

PHOTOSYNTHESIS• In plants light energy is

absorbed by pigments called chlorophyll

• Photosynthesis occurs in the chloroplasts

• Uses CO2 that is released during cellular respiration to make food energy and release oxygen.