Download cell - Jordan High School

Chapter 3
Cells: The Living Units
3-1
3-1: The Study of Cells
 Cell
theory
 Cells are building blocks of life
 Cells are smallest unit of life
 Cells are produced through division of other
cells
 Each cell maintains homeostasis
 Study
3-2
of cells—cytology
An Overview of Cell Anatomy
 Cells
contain:
 Plasma (cell) membrane—surrounds cell
 Cytoplasm—cell contents (organelles, etc.)
3-3
3-1 Checkpoint
1.
The cell theory was developed over
many years. What are its four basic
concepts?
2.
The study of cells is called
3-4
.
3-2: The Plasma Membrane
 Functions
 Separates inside of cell from outside
 Controls entry/exit of substances
 Senses surrounding environment
 Provides structure
3-5
Membrane Lipids
 Phospholipids
compose plasma membrane
 Phospholipid
bilayer
 Hydrophilic heads on outside
 Hydrophobic tails on inside
 O2
& CO2 freely pass through; ions &
other compounds do not
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3-7
Membrane Proteins
 Plasma
membrane proteins can either be
transmembrane or partially embedded
proteins function as receptors,
channels, carriers, enzymes, anchors, or
 Membrane
identifiers
3-8
3-2 Checkpoint
1.
List the general functions of the plasma
membrane.
2.
Which component of the plasma
membrane is primarily responsible for its
ability to form a physical barrier between
the cell’s internal and external
environment?
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3-3: Diffusion & Filtration
 Permeability—substances
cell membrane
enter/leave
 Membrane is selectively permeable
 Types
of movement
 Passive processes—don’t require energy
 Active processes—require energy
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Diffusion
 Diffusion—movement
of molecules from
high concentration to low concentration
 Difference in concentrations is the
concentration gradient
 O2,
CO2 freely diffuse through body cells
 Ions
or large molecules cross the
membrane through channel proteins
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Osmosis
 Osmosis—diffusion
membrane
of water across a
 Occurs until concentration of particles inside
cell equals concentration outside cell
 Water
flows to higher particle
concentration
 “Water flows to where it’s low”
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 Isotonic
solutions
 Concentrations are equal, no water
movement
 Hypotonic
solutions
 Water moves into cell, cell swells
 Hypertonic
solutions
 Water moves out of cell, cell shrinks
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Filtration
 Pressure
 Gases
forces water across a membrane
& nutrients filter through blood
vessels; blood vessels in kidneys filter
blood in the production of urine
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3-3 Checkpoint
1.
What is meant by “selectively
permeable?”
2.
Define diffusion.
3.
How would a decrease in the
concentration of oxygen in the lungs
affect the diffusion of oxygen into the
blood?
4.
Define osmosis.
3-4: Carrier Transports
Carrier-Mediated Transport
 Membrane
proteins carry substances
across the membrane (glucose, etc.)
be passive (high  low conc.) or
active (low  high conc.)
 Can
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 Facilitated
diffusion (no energy)
 Molecule binds to receptor site on
membrane protein
 Protein changes shape & molecule moves
into cell
 Molecule
moves from high  low
concentration
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 Active
transport (requires energy)
 Ions/molecules moved against concentration
gradient into or out of cell
 ATP is needed to push molecules
 Molecule
moves from low  high
concentration
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Vesicular Transport
 Endocytosis—materials
packaged at cell
surface for import into cell (requires
energy)
 Pinocytosis—brings in fluid
 Phagocytosis—brings in solid objects
 Exocytosis—vesicle
fuses with cell
membrane to expel substances out of cell
(requires energy)
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3-4 Checkpoint
1.
What is the difference between active
and passive transport processes?
2.
When certain types of white blood cells
encounter bacteria, they are able to
engulf them and bring them into the cell.
What is this process called?
3-5: Organelles
 Cytosol—intracellular
fluid that contains
nutrients, ions, proteins & wastes
Organelles
 Internal
structures that perform specific
functions
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Cytoskeleton
 Gives
the cell strength & flexibility
 Microfilaments
attach plasma
membrane to cytoplasm
 Microtubules
 Microvilli
materials
give cell strength & rigidity
project from cell & absorb
Centrioles, Cilia & Flagella
 Centrioles
help cell divide
 Cilia
extend from surface, move fluids &
secretions
 Flagella
extend from surface, propel cell
Organelles
 Ribosomes
make proteins
 Can be free or fixed on RER
 Smooth
endoplasmic reticulum (SER)
makes lipids, carbs, hormones
 Rough
endoplasmic reticulum (RER)
makes proteins, delivers to Golgi
 Golgi
apparatus modifies & packages
proteins, repairs plasma membrane
 RER sends vesicles to Golgi; Golgi sends to
cell surface
 Lysosomes
use enzymes to clean up cell,
defend against disease
 Peroxisomes
break down fatty acids
 Mitochondria
provide energy for the cell
 Have a double membrane & cristae (folds)
 Break down glucose to form ATP
 Cells requiring more energy have more
mitochondria
3-5 Checkpoint
1.
Cells lining the small intestine have
numerous fingerlike projections. What
are these structures and what is their
function?
2.
How does the absence of centrioles
affect a cell?
3.
What does the presence of many
mitochondria imply about a cell’s energy
requirements?
3-6: The Nucleus
 Nucleus—control
center for cellular
operations, determines functions
Nuclear Structure & Contents
 Nuclear
 Nuclear
envelope surrounds nucleus
pores allow substances in/out
of nucleus
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 Nucleoli—in
nucleus; make rRNA
 Nucleus
stores DNA in chromosomes
surrounds nucleus
 Unwind in nucleus as chromatin
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Information Stored in the Nucleus
 Nucleus
acids
stores genetic code for amino
 Stored in triplet sequences of A, T, G, C
 Gene—unit
of heredity; contains triplet
sequences to make proteins
3-6 Checkpoint
1.
Describe the contents and structure of
the nucleus.
2.
What is a gene?
3-7: Protein Synthesis
Transcription
 Strand
of mRNA made from DNA
 DNA
strand unzipped, nucleotides form
mRNA on open DNA strand
 G – C, A – U
 Codon—3
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nucleotides (AUG, CGC, etc.)
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Translation
 Protein
made from mRNA strand
 Sequence of codons determines what protein
is made
 mRNA
binds with tRNA in a ribosome
 tRNA contains anticodon to mRNA codon
 Has amino acid attached also
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 Translation
process:
 “Start” codon on mRNA (AUG) begins process
 tRNA anticodon (UAC) binds to mRNA
 Second tRNA arrives with next anticodon
 First tRNA leaves its amino acid on 2nd tRNA
 Process continues until “stop” codon is
reached
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3-7 Checkpoint
1.
How does the nucleus control the cell’s
activities?
2.
During the process of transcription, a
nucleotide was deleted from an mRNA
sequence for a protein. What effect
would this deletion have on the amino
acid sequence of the protein?
3-8: Cell Life Cycle
 Cells
increase in number through cell
division
 Mitosis
occurs during the division of
somatic cells (body cells)
 Meiosis
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occurs in sex cells (ova/sperm)
Interphase
 Most
of cell’s life cycle
 Phases
 G1 phase: growth
 S phase: DNA copied through DNA
replication
 G2 phase: protein synthesis
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Mitosis
 Divides
cell into two identical cells
 Phases: prophase, metaphase, anaphase,
telophase
 Prophase
 Chromosomes visible as pair of chromatids
 Nucleus disappears
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 Metaphase
 Chromatid pair move to center of cell
 Anaphase
 Chromatids separate as daughter
chromosomes; move to opposite cell ends
 Telophase
 Nucleus reforms & chromosome DNA
unwinds
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Cytokinesis
 Cytoplasm
pinches in along middle of the
cell (cleavage furrow)
 Two
daughter cells with identical
chromosomes are formed
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3-8 Checkpoint
1.
Describe interphase, and identify its
stages.
2.
Define mitosis and list its four stages.
3.
What would happen if the spindle fibers
that help divide the cell failed to form
during mitosis?
3-9: Tumors & Cancer
 Tumor—mass
or swelling from excess
cell growth & division
 Benign tumor—seldom dangerous
 Malignant tumor—spread to other tissues
 Metastasis—malignant
other tissues & organs
 Cancer
cells spread to
happens due to malignant tumors
 Cancer cells compete with healthy cells
3-9 Checkpoint
1.
An illness characterized by mutations
that disrupt normal control mechanisms
and produce potentially malignant cells is
termed
.
2.
Define metasasis.