Transcript Cell Structure - walker2015

Cell Structure
Chapter 7
7-1: Introduction to Cells
The Discovery of Cells
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In 1665, Robert Hooke, an English scientist,
used a simple microscope (which magnified
objects 30 times their normal size) to observe
“little boxes” in thin slices of cork.
He called the boxes “cells” because they
reminded him of the small rooms in which
monks lived.
The Discovery of Cells
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In 1675, Anton van Leeuwenhoek, a Dutch
scientist, used a stronger microscope (that
could magnify objects 300-fold)
He named pond water creatures
“animalcules” or “tiny animals”.
First to observe living cells
Cell Theory
1.
2.
3.
All living things are made up of one or more
cells.
Cells are the basic units of structure and
function in organisms.
All cells arise from existing cells.
Looking at Cells
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Cell size is limited by a cell’s surface area-tovolume ratio
Larger cells often have shapes that increase
the surface area available for exchange
Similarities and Differences in
Prokaryotic and Eukaryotic Cells
Average Cell
Size
Cell Wall
Cell Membrane
Nucleus
Cytoplasm
DNA
Prokaryotic
1-10 µm
Eukaryotic
10-100 µm
YES
YES
NO
YES
YES, in
cytoplasm
SOMETIMES
YES
YES
YES
YES, in nucleus
Continuation on next slide
Similarities and Differences in
Prokaryotic and Eukaryotic Cells
Ribosomes
Membrane
Enclosed
Organelles
Mode of
Locomotion
Found in --
Prokaryotic
YES
Eukaryotic
YES
NO
YES
One or more
flagella
Bacteria only
One or two
flagella or cilia
Fungi, protists,
plants, animals
7-2: Inside the Eukaryotic Cell
The Framework of the Cell
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Cytoskeleton – helps the cell move, keep its
shape, and organize its parts
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Microfilaments and microtubules are two types of
cytoskeletons
Directing Cellular Activity
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Nucleus – membrane bound structure that
contains the cell's hereditary information and
controls the cell's growth and reproduction
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The nucleus (nuclei – plural) houses
deoxyribonucleic acid (DNA)
Genetic material in
cells
 Has information to
make proteins
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Directing Cellular Activity
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Nuclear membrane – a double membrane
that surrounds the nucleus
Pores – openings in
the outer nuclear
membrane that
allow substances
to enter and leave the
nucleus
Directing Cellular Activity
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Nucleolus (nucleoli) – small, dark-stained,
round structures that makes ribosomes
Chromatin – DNA is in thread-like form; the
cell is not dividing
Chromosome –
condensed
chromatin; forms a
“X” structure during
cellular division
Directing Cellular Activity
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Ribosomes – Organelles that help in the
synthesis of proteins
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“Free” ribosomes make proteins that remain
inside the cell
“Bound” ribosomes make proteins that are
exported from the cell
Directing Cellular Activity
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Cytoplasm – the gel-like substance found
between the cell membrane and the nucleus
Directing Cellular Activity
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Centriole – one of a pair of organelles that
are found in animal cells that function in the
formation of spindle fibers during cell division
Protein Processing
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Vesicle – (means “small vessel”) Sac-like
membrane that helps store and transport
products produced by cells
Protein Processing
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The endoplasmic reticulum and the Golgi
apparatus are organelles that prepare
proteins for extracellular export
Endoplasmic reticulum (ER) – a network of
membranes throughout the cytoplasm of the
cell
Protein Processing
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Two types of ER
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Rough ER – proteins are made in ribosomes and
then packaged into vesicles
Smooth ER – synthesize lipids in the cell and
helps in the detoxification of harmful substances
in the cell
Protein Processing
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Golgi complex – responsible for sorting and
correctly shipping the proteins produced in
the ER
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Resembles a post office in cells
Storage and Maintenance
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Lysosome – a vesicle that contains specific
enzymes that breaks down large molecules
They also help recycle materials in the cell by
digesting old, damaged, or unused organelles
Lysosomes are in animal cells
Storage and Maintenance
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Mitochondrion (mitochondria = plural) – an
organelle that uses energy from organic
compounds to make ATP
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Mitochondria and chloroplasts have their own
DNA
Storage and Maintenance
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Vacuole – an organelle that stores water,
ions, nutrients, and wastes; it can also store
toxins and pigments
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Animal cells have small vacuoles
When water fills the central vacuole (only in plant
cells), it makes the cell rigid, allowing the plant to
stand upright.
Storage and Maintenance
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Some protists have contractile vacuoles,
which pump excess water out of the cell
Storage and Maintenance
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Chloroplast – an organelle that uses light
energy to make sugar from carbon dioxide
and water
Plant Cell vs. Animal Cell
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Cell wall – provides additional support for
certain cells; they have cellulose which aids
in its structure
Plant Cell vs. Animal Cell
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Organelles that are
exclusively found in
plant cells
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Cell wall
Central vacuole
Chloroplast
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Organelles that are
exclusively found in
animal cells
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Lysosome
Centriole
Picture of animal cell vs. plant cell
Cellular Movement
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Flagella – long finger-like projections that
push cells forward by snakelike wriggling
Cellular Movement
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Cilia – short hair-like projections of certain
cells that beat in a regular fashion to create
currents that sweep materials along
7-3: From Cell to Organism
Levels of Organization
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Cell – the smallest unit of life
Tissue – group of cells that work together and
have a common function
Organ – group of tissues that work together…
Organ system – group of organs…
Organism – group of organ systems…
Cellular Differentiation
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Cellular differentiation – The normal process
by which a less specialized cell develops or
matures to possess a more distinct form and
function