Cell Structure & Function

Cell Theory1. All living things are made of cells2. Cells are the basic unit of life3. All cells come from pre-existing

cells

What do all cells have in common?

1.Genetic information (DNA)

2.Cytoplasm – fluid-filled region between center and cell membrane

What do all cells have in common?3. Cell membrane (plasma membrane) – surrounds cell

◦ Function: regulates what enters and leaves cell

4. Ribosomes – make proteins using instructions from DNA

Animation – Cell Size

How big is a cell?

Surface Area to Volume Ratio•Why are cells so small?•Ratio of surface area to volume •Much greater for small cells

•Space is important for cells to receive nutrients, oxygen, and to remove waste•Volume increases faster than surface area as cells grow•Greater volume= more metabolic reactions BUT more difficult to transport wastes and nutrients•The smaller the cell, the more efficient it is to transport materials across it

Organisms can be:

o Unicellularo Consist of only 1 cell

o Multicellularo Consist of multiple cells

PROKARYOTIC EUKARYOTIC

2 Basic Cell Types

•Smaller/unicellular•Simple•No organelles•No nucleus•Ex: Bacteria

Prokaryotic

Eukaryotic•Larger-multi or unicellular•More complex•Many organelles • Structures that have a

specific function; “mini-organs”

•Nucleus – encloses DNA•Control center of the cell

EukaryoticoEx: Plants, animals, fungi, protistsoUnicellular eukaryotes = Protists

Unicellular Eukaryote

Amoeba

Paramecium

Dinoflagellates

ProtistsWhy are protists eukaryotes if they are only made up of ONE cell?

Prokaryote vs. Eukaryote-What is different between the two types of cells?

Prokaryotes•Simple internal structure•Nucleoid Region (no nucleus)•Flagellum → whip-like tail used for movement

ProkaryotesoPili – short projects that help bacteria attach to surfaces

oMost primitive organisms

Bacteria

E. Coli Strepococcus mutans

Bacteria

Mycobacterium tuberculosisStaphylococcus aureus

Cell Organelles and Functions EUKARYOTIC CELLS INTERNAL STRUCTURE

Eukaryotes

CAN BE SPLIT INTO PLANT AND ANIMAL CELLS

Animal Cell

Animal Cell

Plant cell

Nucleus oFunction: Control center of the celloEukaryotic cells ONLY!!!

Nucleus 3 parts: ◦1.Contains DNA◦A. Chromosome – DNA coiled around proteins called histones◦Humans contain 46 chromosomes in nucleus of all cells ◦ Exceptions: Red blood cells (no nucleus), sex cells

◦B. Chromatin – uncoiled DNA; DNA usually found in this form

Nucleus 2. Nuclear envelope (nuclear membrane) – membrane w/ pores to allow materials in and out of the nucleus

3. Nucleolus – inside the nucleus; makes ribosomes

CytoplasmoOrganelles can be found in the cytoplasmoCytoplasm- portion of the cell outside of the nucleus

Endoplasmic Reticulum(ER) Folded membranes attached to nucleus Smooth ER →

◦Not lined with ribosomes

◦Synthesizes lipids◦Detoxifies chemicals (i.e. liver)

Rough ER◦Lined with ribosomes◦Function: Modifies proteins that are being transported

Ribosomes- made of RNA & protein- Function: Assemble proteins

based on instructions from DNA

C4U Difference between Rough and smooth ER

What are ribosomes? Where can they be found?

Golgi apparatus (golgi body)

Looks like a flattened stack of pancakes Functions:

◦Receives vesicles (sacs) from the ER and finishes, sorts, and ships protein

◦“Packages protein”

One side = receiving; other side = shipping

Lysosomes•Lysosome – Function: Contains powerful digestive enzymes•Digests food particles to release nutrients to cell

Fun Fact enzyme in lysosome destroys skin between fingers/toes during embryo development

Lysosomes◦“Demolition/cleanup crew”◦Destroys damaged organelles◦Ex: neutrophils (WBC) engulf bacteria

◦Produced by the Golgi

Peroxisomes• Functions:• Breakdown fatty acids, H2O2

(catalase), synthesis of myelin (for nerve cells)

• Produced by the ER• Disease: ALD – caused by

peroxisome not functioning properly

Inside the cellWORKING AS A TEAM

Vacuoles

Function: Storage “containers”◦ store various substances

Animals = small and numerous Plants = one large central vacuole◦ Stores mostly water◦ Helps with the structure of a

plant cell

Central Vacuole•Also functions as a large lysosome- contains enzymes which break down materials•Increases turgor pressure (internal cell pressure)

Turgor Pressure

Cell shrinks due to water loss

Cell swells due to influx of water

Vacuoles Contractile vacuole → gets rid of excess water; found in some protists◦Prevents bursting of cell & dilution

Energy Organelles

CHLOROPLAST•Plants only•Some protists and algae•Function:•Site of photosynthesis•Use sun energy to make food energy

Energy Organelles

MITOCHONDRIA

•All eukaryotes•Function:•Site of cellular respiration•Creates energy for cell (ATP) from food

Mitochondria•Contain 2 membranes•Outer membrane•Inner membrane- folded up inside the organelle

Plant cells ONLY!oCell WalloFunction: Rigid layer to protect and support celloKeeps cell from burstingoMade of cellulose (carbohydrate)oChloroplasts – used for photosynthesisoLarge central vacuole

Plant Cell

Cytoskeleton

- network of protein filaments (fibers) that help the cell maintain its shape

• Function: Helps with support/internal structure and movement• Like wood and nails of house

Cytoskeleton

• Made up of microfilaments and microtubules

Cytoskeleton

Microfilaments◦Made of solid globular protein called actin

◦Used for movement and supports shape◦Ex: Muscle contractions

Intermediate Filaments

◦Made of fibrous proteins

◦They reinforce cell shape and anchor organelles◦Ex: Holds nucleus in place

Microtubules◦Hollow tubes of protein called tubulin

◦They often disassemble and reassemble

◦Helps with movement)◦Ex: lysosome may slide along to reach food

◦Ex: movement of chromosomes when cells divide

Movement Both made of microtubules wrapped in membrane Cilia → short and numerous; beat together

◦ Ex: Cells of human windpipe sweep pollen & mucous containing debris from lungs

Flagella → few; long and whip-like

◦ Ex: sperm cells

Centrioles•Type of microtubule •Function: Organize DNA during cell division•ONLY IN ANIMAL CELLS

PLANT ANIMALBOTH

Use these terms to fill in your Venn DiagramCell membrane

Ribosomes

Nucleus

Rough & smooth ER

Chloroplast

Lysosome Cell Wall

Golgi body

Mitochondria

Cytoskeleton

Central vacuole

Centrioles

Small vacuoles