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Cell Structure and
Function
The Discovery of the Cell
• Robert Hooke – first to see and identify cork “cells” using a microscope.
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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.
SchleidenSchwann
Virchow
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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)
Macromolecules
4. 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
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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
Lysosomes
Lysosomes – 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 Vacuoles
Vacuoles
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!
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Osmosis Practice
Cell
90% H2O10% NaCl
80% H2O20% NaCl
Concentration ofwater is greater inthe cell than out, sowater will move out!
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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
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.