Transcript Cell Structure

CHAPTER 7
Cell Structure and
Function
7-1 Life is Cellular
 In
1665, English Physicist Robert
Hooke used one of the first light
microscopes to look at plant tissue.
- he looked at cork.
- he called the tiny chambers he
saw “cells”
CELL THEORY
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Other biologists made further cell discoveries and
came up with statements about cells.
The Cell Theory is a fundamental concept of
Biology.
- The cell theory states the following:
1. All living things are composed of cells.
2. Cells are the basic units of structure and
function in living things.
3. New cells are produced from existing cells.
Prokaryotes and Eukaryotes
 Biologists
divide cells into two
categories: eukaryotes and
prokaryotes.
- Eukaryotes, have a nucleus
- Prokaryotes, no nucleus
Cell Structure
Chapter 7 Sec 2
Cell Walls
Found in plants, algae, fungi, and most
prokaryotes.
 Main function is to provide support and
protection to the cell.
 Made of fibers of carbohydrates called
cellulose.
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Nucleus
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Founded in 1831 by Scottish botonist Robert
Brown
Controls most cell processes
Contains DNA
Holds the coded info for making proteins and
other required molecules
Chromatin is visible in the nucleus
Chromatin is DNA bound to protein
During cell division, chromosomes form when
chromatin condenses.
Chromosomes hold genetic info which pass from
one generation to another
 The
nucleolus, a small dense region,
is also found in most nuclei.
 Ribosomes’ assembly begins in the
nucleolus.
 The nuclear envelope is the double
membrane layer which surrounds the
nucleus.
Cytoskeleton
The cytoskeleton is a network of protein
filaments to support cell shape.
 Also aids in cell movement.
 Made up of microtubules and
microfilaments.
 Microtubules are hollow tubes of protein.
They give cell shape, and work as tracks
for organelle movement.
 Microfilaments are long, thin fibers that
function in support and movement of the
cell.
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Ribosomes
 Ribosomes
are small particles made
of RNA (ribonucleic acid) and protein.
 Proteins are assembled on
ribosomes.
 2 Types of ribosomes:
1. attached ribosomes
2. free ribosomes
Endoplasmic Reticulum (ER)
 Found
in Eukaryotic cells
 It is an internal membrane structure.
 The ER assembles components of the
cell membrane and modifies some
proteins.
 Rough ER is involved in the synthesis
of proteins.
 Smooth ER does not have ribosomes
on its surface.
Golgi Apparatus
 Proteins
from the rough ER move
into the stack of membranes known
as the golgi apparatus.
 Enzymes in the golgi apparatus
attach carbs and lipids to proteins.
 From the golgi apparatus, proteins
are sent to their final destination.
Lysosomes
 Lysosomes
are small organelles filled
with enzymes.
 Break down lipids, carbs, and
proteins from food.
Vacuoles
 Vacuoles
store materials such as
water, salts, proteins, and carbs.
Chloroplasts
 Found
in plants
 Uses energy from the sun to
complete the process of
photosynthesis
Mitochondria
 Release
energy from stored food
molecules
 Uses energy from food to make high
energy compounds
 Energy produced is used to power
growth, development, and
movement.
 Known as the “power house” of the
cell
Organelle DNA
 Chloroplasts
and mitochondria
contain some of their own genetic
information in the form of DNA
 Biologist Lynn Margulis suggested
mitochondria and chloroplasts are
decendants of ancient prokaryotes
 In humans, all of our mitochondria
come from the cytoplasm of the egg
cell….thank you Mom!
The Cell as a Factory
 The
way proteins are made in a cell
is similar to the way products are
made in a factory:
– Cell membrane
– Cell wall
– Nucleus
– Ribosomes
– Endoplasmic reticulum
– Golgi apparatus
– Lysosomes
– Vacuoles
-Mitochondria
-Chloroplasts
-Cytoskeleton
Comparing Cells
 Prokaryotes
have cell membranes
but no nuclei
 Eukaryotes are much larger than
prokaryotes and contain nuclei
 Eukaryotes have specialized
organelles
 Plant cells (eukaryotes) contain large
vacuoles, cell walls, and chloroplasts
 Animal cells (eukaryotes) do not
have cell walls or chloroplasts