Transcript Cell Structure and Functionx

Cell Structure and
Function
Anderson
Spring 2017
College of the Redwoods
What is a cell?
 Fundamental unit of LIFE! (Smallest unit of a living thing)
 Teeny tiny so we have to use a microscope to see them
Two Types of Cells
Prokaryotic
Eukaryotic
 Bacteria
 Animal
 Archaea
 Plant
 Fungi
 Protists
Common Cell Components
All cells share 4 common components
1. Plasma membrane – outer covering that separates the
inside from its surrounding environment
2. Cytoplasm – jelly-like region inside cell where
organelles are found
3. DNA – genetic material
4. Ribosomes – particles that synthesize proteins
Components of Prokaryotic Cells
 Unicellular
 NO nucleus (central thing that holds DNA in eukaryotic cells)
 DNA contained in nucleiod (no membrane)
Pili/
 Cell wall
 Differ between bacteria
and archaea
 Capsule (some)
 Surface attachment,
protection, resistance
 Flagella, pili, fimbriae
Eukaryotic Cells
 Contain membrane-bound organelles
 Have central nucleus (with membrane)
 Come in all shapes and sizes
Plasma Membranes
Also surrounds organelles
Plasma Membranes

Phospholipid bilayer

Regulates and prevents passage of some
substances

Actively bring in/removes substances

Some compounds move passively
through
1. Phospholipids
2. Embedded
proteins
3. Cholesterol
4. Carbohydrates
Cytoplasm/Cytoskeleton
Cytoplasm
 Contents of the cell between plasma membrane and
nuclear envelope (center where the nucleus is)
 Made up of cytosol (gel-like substance), cytoskeleton,
and other chemicals
 70-80% water
 Full of organic molecules and ions
 This is where all the organelles hang out
Cytoskeleton
 Network of protein fibers that:
 Three types of fibers
1.
Help to maintain shape of cell
 Microfilaments (actin
2.
Secures organelles is specific
position
 Intermediate filaments
3.
Allows cytoplasm and vesicles
to move within the cell
4.
Enables unicellular organisms
to move independently
filaments)
 Microtubules
(we’ll talk more about these during
mitosis)
Flagella
(flagellum)
Cilia
(cilium)
 Long hair-like structures
 Short hair-like structures
 Just one or few
 Many in number
 Used to move entire cell
 Used to move entire cell
extending from plasma
membrane
extending from plasma
membrane
 Move substances along outer
surface of cell
Endomembrane System
(organelles surrounded by membranes)
Nuclear envelope
Endoplasmic reticulum
Lysosomes
Vesicles
Golgi apparatus
Nucleus
 Nuclear envelope

Double-membrane
phospholipid bilayer structure

Covered in pores to control
passage of ions, molecules, and
RNA
 Chromatin = DNA and proteins

Exists in the form of
chromosomes
 Nucleolus – creates ribosomes
 Nucleoplasm – gel-like
substance in the nucleus
Endoplasmic Reticulum
Interconnected membranous tubules that modify proteins and synthesize lipids
Rough ER
 Covered in ribosomes
(proteins that make proteins)
 Newly synthesized proteins
get modified in lumen
(cisternal space)
 Folded or addition of
sugars
 Makes phospholipids for
membranes
Smooth ER
 No ribosomes
 Synthesis of carbohydrates,
lipids, and steroid hormones
 Detoxification
of
medications/po
isons
 Metabolizes
alcohol
 Stores calcium
Golgi Apparatus
 Molecules not destined
to stay in rough ER will
be packaged into
vesicles
 These transport vesicles
need to be sorted,
packaged, and tagged,
which happens in the
Golgi apparatus
 Cis face = receiving end
 Trans face = releasing
end
 Can have more than 1
per cell – secretory cells
have lots of Golgi!
Lysosomes
 Contain digestive enzymes
to break down leftover cell
bits
 Digests ingested food for
single-celled eukaryotes
 Come from the Golgi
apparatus
 Destroy disease-causing
organisms by phagocytosis
Vesicles and Vacuoles
 Vesicles are membrane-bound
sacs
 Storage and transport
 Small and usually many
 Membranes can fuse with
other membranes
 Contractile vacuole – regulates
water to keep unicellular
organisms from swelling or
shrinking
 Vacuoles are larger vesicles
 Storage and transport
 Membranes don’t fuse with
other membranes
 Central vacuole in plants –
regulates water
Mitochondria
Mitochondria
 “Powerhouse” of the cell
 Make adenosine triphosphate
(ATP) – cell’s main energy
molecule
 ATP is made from the
breakdown of glucose – this is
cellular respiration
 Have their own ribosomes and
DNA
 Cells that need lots of energy
(muscle cells) have lots of
mitochondria
Peroxisomes
 Round organelles with single membrane
 Break down fatty acids and amino acids via oxidation
reactions
 Detoxify poisons (alcohol) – lots in liver
 Break down hydrogen peroxide (H2O2), a byproduct of
oxidation, which is toxic to cells
 Bud from the endoplasmic reticulum
Cell Wall
 Found in plants, fungi, protists
and prokaryotic cells – NOT
ANIMALS!
 Rigid covering outside plasma
membrane
 Protects, provides structural
support, and give shape to cell
 Made up of cellulose (long
strands of glucose) in plants
 Made up of peptidoglycan in
prokaryotes
Chloroplasts
 Function in photosynthesis
(making glucose from sunlight)
 Chlorophyll – green pigment that
captures sunlight for energy
 Located in thylakoid
Central Vacuole
 Regulates plant cell’s
concentration of water
 Provides turgor pressure
(outward pressure)
 Water moves from high to low
concentrations – out of the
plant and into soil when you
forget to water!
Animal vs. Plant Cells
Organelle
Animals
Plants
Plasma Membrane
Yes
Yes
Cytoplasm
Yes
Yes
Nucleus
Yes
Yes
Endoplasmic reticulum
Yes
Yes
Golgi apparatus
Yes
Yes
Lysosomes
Yes
Yes
Vesicles/Vacuoles
Yes
Yes
Mitochondria
Yes
Yes
Cell wall
No
Yes
Chloroplasts
No
Yes
Central Vacuole
No
Yes
Think about it this way
A cell is a big manufacturing company
1.
The membrane is the exterior walls with doors and windows to let only certain
things in/out – plants have an extra wall (fence?)
2.
The nucleus is the CEO, where all the information comes from
3.
The endoplasmic reticulum is the manufacturing floor (proteins)
4.
Ribosomes are the workers doing the manufacturing
5.
The Golgi apparatus is the shipping department
6.
Vesicles are vehicles that transport goods inside the company
7.
Lysosomes are the recycling plant/compost pile
8.
Mitochondria are the power stations keeping everything running
9.
Chloroplasts are the kitchen for manufacturing PLANTS (pun intended!)
Socrative Time
Have you been paying attention?!