Download Cells Structure and Function

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Anton van Leeuwenhoek (1600’s)-first to spot the
living organisms in pond water using an early
microscope
Robert Hooke-(1665) viewed thin layers of plant cells
under microscope, coined the term “cells”
Cell Theory
 All living things are composed of cells
 Cells are basic units of structure and function in
living things
 New cells come from previously existing cells
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Cells range in size from 5 micrometers
(bacteria) to 1000 micrometers (amoeba Chaos chaos)
All cells have:
 Cell membrane: thin, flexible barrier around the cell
 Some cells have a cell wall surrounding the cell membrane
(plant cells)
 Nucleus: contains genetic material and controls cell
activity
 Cytoplasm: material inside cell membrane excluding the
nucleus
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Prokaryotes: cells with cytoplasm and cell
membranes but NO nucleus
Prokaryote example: bacteria
Eukaryotes: cells with nuclei and organelles
Eukaryotes can be single celled organisms or
part of a larger organism
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Cell walls: found in plants, algae, fungi, and
most prokaryotes, but not in animal cells
Cell wall provides support and protection for
the cell
Cell wall made from carbohydrate and
protein
Plant cell walls are composed mostly of
cellulose
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Nucleus contains the genetic information of a
cell (DNA) and controls most cell processes
Chromatin: granular material visible inside a
cell
Chromatin condenses during cell division to
form chromosomes (contains genetic
information)
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Nucleolus-small, dense are within the nucleus
which ribosomes are assembled.
Ribosomes aid in intracellular protein
production
Nuclear Envelope-surrounds the nucleus,
allows some material to move in and out of
nucleus (RNA)
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Cytoskeleton is a network of protein
filaments that helps maintain the shape of
the cell.
Cytoskeleton also aids in cell movement
Microtubules assist in cell division, helping
chromosomes to separate
Microtubules also may form cilia and
filaments
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Microfilaments are long, thin fibers that
function in cell movement and support
The cytoskeleton also helps in moving
organelles within the cell
Ribosomes-proteins are assembled in the ribosomes
Endoplasmic reticulum-components of the cell
membrane are assembled and some protein
modification occurs
 Golgi apparatus-enzymes attach carbohydrates and
lipids to proteins
 Lysosomes-contain enzymes which help breaking
down lipids, carbohydrates, and proteins into a
usable form for the cell
 Lysosomes also help break down organelles that are
no longer useful to the cell
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Sac-like structures that serve as storage
structures within a cell
Water, salts, proteins, & carbohydrates may
require storage
Pressure within plant vacuoles provide some
structural support to help hold up leaves &
flowers
Vesicles are smaller vacuoles sometimes
involved in transport
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Chloroplasts contain chlorophyll, which can
convert sunlight into energy rich molecules
Chloroplasts are Natures original solar cells
Only green plants and some algae contain
chlorophyll.
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Release energy from food molecules
Specifically, mitochondria use energy from
food to make high energy compounds that a
cell can use for growth, development, and
movement
Mitochondria are found in almost all
eukaryotic cells
Chloroplasts and mitochondria contain some of their own
genetic information (DNA)
This DNA controls the function of the cell
The cell functions in much the same way that a factory does.
Walls & roof-cytoskeleton
Transportation within the factory-cytoskeleton
Main office-nucleus sends out instructions (RNA)
Ribosomes-factory machine turning out
Customizing shop/shipping-Golgi Apparatus
Power plant-mitochondria/chloroplasts
The cell membrane controls what goes in/out of the
cell and provides protection and support.
Diffusion is movement of a substance to move through/across a cell
membrane. It does NOT require energy to do this.
Material will move from a higher concentration to a lower concentration,
with goal being equilibrium of the concentration.
Concentration is the amount of solute in a given amount of solvent, thus
making a solution of a particular concentration
Permeable-a membrane that allows a substance to cross it is “permeable”
to that substance
Impermeable-A membrane that DOES NOT allow substances to cross it is
“impermeable”
Osmosis is the diffusion of water through a selectively permeable
membrane
Osmosis will occur across a membrane until an “isotonic” condition is
reached. (Isotonic literally means “ equal strength”
HypertonicHypotonic-
Osmosis exerts a pressure (osmotic pressure) on the hypertonic side of a
selectively permeable membrane
Cells (containing salts, sugars, proteins, etc will be hypertonic to fresh
water, thus there will be a net movement of water into a cell.
This will cause a cell to swell up, potentially bursting.
Why does this not usually happen?
Because cells body cells are rarely if ever surrounded by pure water.
What about cells such as bacteria and plant cells that may be surrounded
by fresh water? Why don’t they burst?
Because they have a tough cell wall which restricts expansion.
Facilitated diffusion is when a specific protein assists a particular molecule
to move across a membrane from a hypertonic to hypotonic situation
Example: RBC (red blood cells) use a specific protein to allow glucose to
pass through the membrane
A movement of materials across a membrane from lower to higher
concentration (swimming upstream!)
Active transport acts like a pump, thus it requires energy.
Endocytosis-process of taking materials into a cells by infoldings or
pockets of the cell membrane
Phagocytosis-large particles taken into a cell by endocystosis
Exocytosis-removal of large amounts of material from a cell
Unicellular Organisms may be-eukaryotic or prokaryotic
--live as individual cells or in a colony
A colony is a group of individual cells that live together but have some
specialized structures and specialized functions
Multicellular organisms have specialized cells that that perform particular
functions within the organism
Human body has many examples of specialized cells that do a particular
job for the body to live (RBC, WBC, pancreatic cells, etc
Cells combine to form-
Tissues, which combine to makeOrgans, which work together to makeOrgan systems
Cells-division of labor among cells of multicellular organisms
Tissues-organized, specialized cells working together
4 types of tissue in most organisms
muscle
epithelial (skin)
nervous
connective (bone, blood, cartilage, lymph)
Tissues working together for a common cause in an organism is an organ
Organ system is a group of organs that work together
Human body contains 11 major organ systems includingMuscular
Skeletal
Circulatory
Nervous
And many more!