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Cell Structure and Function
What is a cell?
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Smallest particle or building block of life
Made up of four elements – (CHON)
Majority of structure is protein
Vary in size (2 micrometers to over a
meter)
Shape controls function
Example: white blood cells destroy bacteria
What is Cytology?
The study of the structure and
the function of cells.
What is the main structure of a
cell?
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Nucleus - contains DNA
Plasma membrane - lipid bilayer barrier
that separates the inside with outside
environment of the cell
Cytoplasm – cellular material outside the
nucleus and inside the plasma membrane
What are organelles?
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Found in the cytoplasm
Metabolic machinery
Different Types
1)
2)
3)
Endoplasmic reticulum – fluid-filled tubules that
twist in cytoplasm (smooth ER vs. rough ER)
Golgi apparatus – flat membranous sac that
packages proteins
Mitochondria – sausage-shaped that help make ATP
for energy
What are the organelles?
1)
2)
3)
4)
5)
Ribosomes – tiny, round proteins that allow protein
synthesis
Lysosomes – membrane bags that have digestive
enzymes to get rid of foreign substances
Peroxisomes – membranous sacs that use oxygen to
get rid of harmful substances
Cytoskeleton – network of protein structures that
gives internal framework
Centrioles – rod-shaped bodies that form the mitotic
spindle during cell division
Cell Structure Drawing
Cell Structure Drawing
Cell Structure Drawing
What are the main functions of the
cell?
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Metabolize
Digest foods
Get rid of wastes
Reproduce
Grow
Move
Respond to a stimulus (irritability)
What are two types of membrane
transport?
1.
Passive transport – no energy is needed
to transport substances through cell
membrane
a)
b)
diffusion – particles that are in random
motion and move to an area where there is
less particles
filtration – water and solutes are forced
through a membrane by fluid or hydrostatic
pressure
What are two types of membrane
transport?
2.
Active transport – the use of ATP
(energy) to move substances across the
membrane
a)
b)
solute pumping – the use of protein solute
pumps to get substances across membrane
(sodium-potassium pump)
bulk transport – endocytosis (phagocytosis)
vs. exocytosis
What are the types of diffusion?
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Simple diffusion – no assistance is needed
to get particles or solutes across the
plasma membrane
Osmosis – the movement of water across
the plasma membrane
Facilitated diffusion – proteins in the
plasma membrane are needed to get
certain substances (glucose) across
Diffusion Drawings
Active Transport Drawing
Sodium-Potassium Pump Drawings
Bulk Transport Drawing
What is cell division?
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Interphase – cell growth & metabolic
activity
Cell division (2 parts)
a)
b)
Mitosis – 4 phases (prophase, metaphase,
anaphase, telophase)
Cytokinesis – division of the cytoplasm to
make two daughter cells
Mitosis Diagram
What is protein synthesis?
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Need DNA (genes)
Need RNA
1)
2)
3)

mRNA
tRNA
rRNA
Two Steps (2 T’s)
1.
2.
transcription – DNA is copied into mRNA
translation – mRNA is decoded to make proteins
Protein Synthesis Diagram