Transcript Cell Structure and Function

CELLS
Structure and Function
Cell = smallest unit of life
Microtubules
Intermediate filaments
Actin filaments
Centrioles
Centrosome
Lysosome
Vesicle
Cytoplasm
Nuclear Envelope
Chromatin
Nucleolus
Rough ER
Smooth ER
Ribosomes
Mitochondrion
Polyribosome
Golgi apparatus
Endoplasmic
Nucleus
Reticulum
Cytoskeleton
Features of the Human Cell
Organization of the Cell
• Plasma Membrane
– boundary surrounding the cell
• Genetic material: DNA
– located in a membrane-bound nucleus
for eukaryotic cells
• Cytoplasm
– Semi-fluid matrix containing enzymes
and organelles
(enzyme = biological catalyst)
• Cytoskeleton
– network of filaments and tubules in cytoplasm
that maintains cell shape, allows movement
Functions of Cell Features
Structure
Function(s)
1. Regulates passage of
Plasma
materials into and out of cell
Membrane
2. Cell-Cell Recognition
Functions of Cell Features
Structure
Nucleus
Function(s)
1. Carrier of genetic material
DNA + protein = chromatin
2. Governs cell activities
3. Directs cell reproduction
4. Surrounded by Membrane
= nuclear envelope
5. Contains nucleolus—
produces ribosomes
Functions of Cell
Features
Structure
Function(s)
Ribosomes 1. Site of protein synthesis
2. Can be free in cytoplasm
or attached to membranes
Functions of
Cell Features
Structure
SER
RER
Function(s)
Rough
Endoplasmic
Reticulum (RER)
1. Produces proteins
2. Prepares proteins for export
Smooth
Endoplasmic
Reticulum (SER)
1. Lipid Synthesis
2. Drug detoxification
3. Transport of proteins from RER
Functions of Cell
Features
Structure
Function(s)
Golgi
Apparatus
Collects, modifies, packages and
distributes proteins and lipids from ER
Functions of Cell
Features
Structure
Lysosome
Function(s)
Contains digestive enzymes
to digest food in protists or
destroy aging organelles
Endomembrane System
Rough
Endoplasmic
Reticulum
Smooth
Endoplasmic
Reticulum
Vesicle
Golgi
Apparatus
Vesicle
Lysosome
Vesicle
Plasma
Membrane
Functions of
Cell Features
Structure
Peroxisome
Function
Removes harmful oxidants
from cells
Functions of Cell
Features
Structure
Mitochondrion
Function
Captures energy from
organic molecules,
producing ATP
Functions of
Cell Features
Structure
Function(s)
Cytoskeleton
1. Maintains cell shape
2. Anchors organelles and proteins
3. Allows for organelle movement
and cellular movement in some
cell types
Functions of
Cell Features
Structure
Function
Centriole
Gives rise to basal bodies that
produce cilia or flagella
Functions of
Cell Features
Structure
Centrosome
Function
Organizes microtubules
that attach to chromosomes
in nuclear division
Functions of Cell Features
Structure
Cilia and
Flagella
Function(s)
1. Move substances across
cell surface in lungs,
fallopian tubes
2. Cell movement in sperm
Connections Between Cells
Tight Junction: joining of proteins
creates impermeable barrier
Gap Junction: adjacent channels
allow communication
Adhesion Junction: filaments of cytoskeleton connect cells, allow stretch
Functions of Plasma Membrane Components
Cell-cell recognition
plasma membrane
carbohydrate
chain
Controls
access
hydrophobic
tails
Outside
hydrophilic
heads
phopspholipid
bilayer
filaments of cytoskeleton
cholesterol
Inside
Regulates fluidity
proteins
Transport, signal reception, recognition
Diffusion: Movement from from high  low
concentration to reach equal distribution
- +
charged molecules and ions
H2O
Diffuses through pores
in membrane proteins
aquaporin
uncharged
molecules
-
+
Freely diffuse
through
phospholipid
bilayer
macromolecule
phospholipid
molecule
protein
Membrane
is
permeable
to water
only, net
movement
of water to
inside
Osmosis: Diffusion of Water Across a
Selectively Permeable Membrane
Isotonic solution
maintains cell
shape
Cells gain water in a
Hypotonic (lower salt)
solution
Equal
movement
into and
out of cell
when
equilibrium
is reached
Cells lose water in a
Hypertonic (higher salt)
solution
Facilitated Transport:
Use of Carriers to Assist with Diffusion
Outside
K+
carrier
protein
glucose
Inside
Active Transport with Protein Carrier: Requires
energy to transport from low  high concentration
Outside
K+
K+
K+
P
ATP
ADP
K+
Inside
K+
Transporting Large Substances
Endocytosis
Formation of a
vesicle from
the plasma
membrane to
take in large
substances
vesicle
vesicle
Exocytosis
Fusion of a
vesicle with
the plasma
membrane to
release large
substances
Summary of Transport Mechanisms
• Passive: Do not require energy input
– Diffusion
– Osmosis
– Facilitated Transport
• Active: Require energy input
– Active Transport
– Endocytosis
– Exocytosis
Cellular Respiration:
Producing ATP from Glucose
Inside cell
electrons
transferred
by NADH
glucose
Requires
Oxygen
electrons
transferred
by NADH
Citric
acid
cycle
Glycolysis
glucose
pyruvate
Electron
Transport chain
oxygen
mitochondrion
2
ATP
2
ATP
32
ATP
Outside cell
Energy Yield from Glucose
Without Oxygen, Fermentation Occurs
Needed to continue glucose
breakdown for energy
NAD+
fermentation
cytoplasm
Electron
carrier
produced in
glycolysis
fermentation
lactate
when oxygen is
available
Training reduces
Fermentation
Enzymes: Biological Catalysts That Speed
up the Rates of Metabolic Reactions
Substrate
1 Substrates
enter active
site
Substrate
Active
Site
Enzyme
3 Product released;
enzyme ready again
2 Shape change
promotes reaction