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Cell Structure & Function
Life is Cellular
A little history… 1600s: van Leeuwenhoek used microscope to study
nature
1665: Hooke used microscope to look at plant tissue & cork; called them “cells”
1838: Schleiden concluded that all plants
were made of cells
1839: Schwann concluded that animals are made of
cells
1855: Virchow studied cell reproduction and concluded that cells come from cells
What is a cell?
The basic unit of ALL living
organisms.
Scale of Life
Cell Theory
All living things are composed of cells.
Cells are the basic units of structure & function in living things.
New cells are made from existing cells.
Types of cells:
Prokaryotes
Eukaryotes
Prokaryotes
Unicellular No nucleus Asexual
reproduction
Example: bacteria
Eukaryotes Unicellular or
multicellular Nucleus present Organelles present Sexual reproduction
Examples: plants, animals, people
All cells have:
Cell membrane Cytoplasm Ribosomes Cell wall (plants
only)
Cell membrane
The “skin” of the cell.
Protects cell from outside
environment. Regulates flow of
water, nutrients & waste.
Cytoplasm
Material inside the membrane (not including the nucleus).
Contains many important structures.
Other cell parts to know:Cell Wall Found outside cell membrane Supports & protects cell Plant cells only!!!
Cytoskeleton Maintains shape MovementNucleusOrganelles
Nucleus
The “brain” of the cell.
Controls cell functions.
Contains DNA. Surrounded by
nuclear envelope.
Organelles
”Little organs” Specialized parts of the cell.
Examples: ribosomes, mitochondria, chloroplasts, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles
Cell Transport
Cell Membrane Functions:• Provides protection and support.• Regulates what enters
and leaves the cell.• Takes in food and water.• Eliminates waste.• Allows the cell to maintain
homeostasis.
The cell membrane is semi-permeable.
Some substances can pass through it, while others cannot.
Most biological membranes are semi-permeable.
Parts of the Cell Membrane
Phosopholipid bilayer: the core of the membrane; forms a strong barrier between the cell and the outside
Protein channels: form pumps to move material through membrane
Carbohydrates: identify the cell; on the outside
Concentration How many molecules are in a given volume. (How
crowded the molecules are.)
Concentration = Amount of solute Volume of Solution
Every cell is surrounded by liquid and has a liquid interior (cytoplasm) that are solutions of many different substances.
High Concentration Low Concentration
Passive Transport: movement from an area of high concentration to
areas of lower concentration (getting less crowded)
Diffusion
Facilitated Diffusion: molecules that are too large to pass through the cell membrane go through protein channels
Osmosis: the diffusion of water
Osmosis in Cells
Hypotonic: the solution outside has a lower solute concentration that inside the cell.
Isotonic: the concentration of solutes is the same both in and out of the cell
Hypertonic: the solution outside has a higher solute concentration than inside the cell
Active Transport: movement from an area of low concentration to areas of higher concentration
(getting more crowded) Exocytosis: when a vesicle fuses with the
cell membrane to take material out
Endocytosis: brings material into the cell when a pocket in the membrane breaks off, forming a vesicle1.) Phagocytosis: large particles
taken in2.) Pinocytosis: small particles
taken in
Homeostasis & Cells
Cells in multicellular organisms are interdependent.
Cells in multicellular organisms are specialized to perform particular functions in the organism.
Cell Specialization
Cells – Tissues- Organs- Organ Systems- Organism
The basic unit of life.
Cell
A group of cells that perform a particular function.
Four types: Connective Epithelial Muscle Nervous
Tissue
A group of tissues working together to perform a particular function.
Examples: Heart Stomach Lungs
Organs
A group of organs working together. Examples:
Nervous system Circulatory system Digestive system
Organ System
Any living thing.
Organism
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