Cell Structure & Function

Cell Theory All living things are made of cells Cells are the basic unit of life All cells come from pre-existing cells

What do all cells have in common? Genetic information (DNA) 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

How big is a cell? Animation – Cell Size

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: Unicellular Consist of only 1 cell Multicellular Consist of multiple cells

2 Basic Cell Types PROKARYOTIC EUKARYOTIC

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

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

Eukaryotic Ex: Plants, animals, fungi, protists Unicellular eukaryotes = Protists

Unicellular Eukaryote Protists Why are protists eukaryotes if they are only made up of ONE cell? Amoeba Paramecium Dinoflagellates

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

Prokaryotes Most primitive organisms Pili – short projects that help bacteria attach to surfaces Most primitive organisms

Bacteria E. Coli Strepococcus mutans S. Mutans causes tooth decay. E. coli causes vomiting, diarrhea, abdominal pain. E. Coli Strepococcus mutans

Bacteria Mycobacterium tuberculosis Staphylococcus aureus Staph infections (MRSA as well). Mycobacterium tuberculosis Staphylococcus 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 Function: Control center of the cell Eukaryotic 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

Cytoplasm Organelles can be found in the cytoplasm Cytoplasm- 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) Smooth ER also detoxifies drugs. Liver cells have A LOT of smooth ER.

Rough ER Ribosomes- made of RNA & protein 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 Tay Sachs disease caused by lysosomes that fail to function properly. Components of the cell membranes build up in nerve cells and usually cause death by the age of 4.

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 ALD (adrenoleukodystrophy) caused by build up of fatty acids in nerve cells. Often leads to a vegetative state.

Inside the cell Working as a TEAM

Vacuoles Function: Storage “containers” Animals = small and numerous 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 All eukaryotes Function: 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! Cell Wall Chloroplasts – used for photosynthesis Function: Rigid layer to protect and support cell Keeps cell from bursting Made of cellulose (carbohydrate) Chloroplasts – used for photosynthesis Large 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

Cytoskeleton Made up of microfilaments and microtubules

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 ANIMAL BOTH

Use these terms to fill in your Venn Diagram Cell membrane Golgi body Mitochondria Rough & smooth ER Nucleus Cytoskeleton Ribosomes Central vacuole Chloroplast Centrioles Lysosome Cell Wall Small vacuoles