Cell Structure and Function

Cell Theory• All living organisms are made

of cells. • Cells are small• aqueous solution (cytoplasm)• organelles (subcellular

structures) “subunit of life!”• Cells are of different size and

shape• Size and shape can be related

to its specific function.• Called specialized Cells

What’s inside the cell?

Are there different types

of cells?

From Prokaryote to

Eukaryote• All living things come from a

single cell born 3,500 million years ago (mya)– Simple organic molecules likely

formed billions of years ago

1. A prokaryote “ate” another prokaryote

2. The inner prokaryote helped the outer prokaryote

3. They lived happily ever after

Primordial Cell

How did organelles get into simple cells?Endosymbiotic Theory

Prokaryotic Cells

Examples?

•“Before membrane or nucleus”•NO Nucleus•Only ribosomes, DNA, and cytoplasm inside•Extremely Simple

BACTERIA

Examples?

Eukaryotic Cells

•“TRUE membrane or nucleus”•Nucleus and membrane bound organelles PRESENT•DNA in nucleus•Extremely COMPLEX

Plants, animals, and Fungi

Unicellular vs. Multicellular Organisms

• Why unicellular?

• Why multicellular?

•Simplicity•Quick Reproduction (Asexual)•No need for circulatory system

•Complex•Specialized •Sexual Reproduction= genetic differences•Need a circulatory system to get nutrients

Why don’t we have enormous

unicellular organisms wondering

around Walmart?

• It takes to long to get nutrients throughout the cell

• LAB TIME!• Let’s see how the

surface to volume ratio affects nutrient supply to the cell.

Outside CoversPlasma/cell Membrane

Cell Wall

• Flexible membrane• Phospholipid bilayer• Controls what goes in and comes out• All Cells!

• Rigid structure made of cellulose (carbohydrate) holds plants up

• Extra Protection• Plant and bacterial cells (no animals)

Inner structures

Nuclear Envelope

Nucleus

Nucleolus

•The outside covering of the nucleus

•Controls all cell activities•Hold all genetic information (DNA)•”Brain of the cell”

•Inside the nucleus•makes ribosomes and nucleic acids for the nucleus

Some cells lose their nucleus as they mature Ex/ RBC’s

Ribosomes • Make proteins!– Assembled by their

instructions in DNA• “Ribs” are delicious protein

Inner Structures

Cytoplasm • Clear jelly-like fluid inside of a cell.

• Holds organelles in place• Multiple chemical reactions

take place here.• Kept out of

nucleus by nuclear envelope.

Inner Structures

Endoplasmic Reticulum

• Folded membrane in the cytoplasm

• Has large surface area for more chemical reactions.

• Creates containment vesicles

• Studded with ribosomes• Creates Proteins

Smooth ER

Rough ER

Golgi Apparatus • Closely stacked, flattened membrane sacs

• Receive newly made proteins and lipids from the ER

• sends both to the plasma membrane and other organelles throughout the cell.

Vacuole• Stores food, enzymes, and

other materials needed by a cell.– A small percentage of vacuoles

store waste products.– Vacuoles in plants cells are huge!• Usually only one.

– Animal cells can have many small vacuoles.

Lysosomes• Contain digestive enzymes.• Digest excess or worn out

organelles, food particles, and engulfed viruses or bacteria

• Their membrane prevents harmful enzymes from pouring into the cytoplasm of the cell.

• “Everyone wants to get rid of lyce”

Mitochondria • food molecules are broken down (glucose) to produce energy.

– Shaped like tiny sausages.– Have their own DNA/Ribosomes– Inner membrane forms long,

narrow folds called cristae.

Chloroplasts • Photosynthesis takes place here

• Transforms light energy into chemicals to produce food

• In plants only!

• green pigment that traps light energy

• gives plants their green color.

• In the thylakoid membrane of the chloroplast.

• **What gives plants their green color**

Contain Chlorophyll

Centriole • Thick part of the cell membrane where spindles attach

• Helps in cell reproduction• Helps in cell division

Structures for Support

Cytoskeleton

made of…

• provide support for organelles and helps the cell maintain its shape.

– Microtubules: Thin, hollow cylinders of protein.

– Microfilaments: Thin, solid protein fibers.

Structures for Movement

• “Hair-like projections” that beat together to create movement

• whip-like tail for motion–major method of

locomotion in unicellular organisms.

Cilia

Flagella