Transcript Cell Membrane

Cell Structure and
Function
Chapter 7
Characteristics of Living
Things
Page 16
Levels of Organization
Page 21
Cell Size and how we know
The Diversity of Cellular Life
Unicellular - single celled
organisms, exhibit all the
characteristics of life
Can be both Eukaryotic and
Prokaryotic
Multicellular - made up of
many cells and all cells are
interdependent
Each has a specific function
that contributes to the
whole (specialization of
roles)
The Cell Theory
All living things are
composed of cells
Cells are the basic units of
structure and function in
living things
New cells from existing cells
Two Categories of Cells
Prokaryotes
no Nucleus
smaller, simpler cells
Example: Bacteria
Eukaryotes
Have a Nucleus
Have Organelles
examples: Plant cells and
animal cells (pg 174 fig 7.5)
Comparing Cells
Chart on page 183
Structure and Function
Cell Membrane
The cell membrane regulates
what enters and leaves the
cell and provides protection
and support
Cell Membrane
(pg 184 fig 7-15)
Phospholipid
bilayer
Semi-permeable
Some substances can cross
and others can’t
Protein molecules run
through the lipid bilayer
Carbohydrate molecules
attached to outer surfaces of
proteins
Concentration - mass of
solute in a give volume of
solution
Isotonic - same strength
Hypertonic - above strength
Hypotonic - below strength
Diffusion
Molecules in solution move
constantly and spread
randomly through space.
They naturally move from an
area of high concentration to
an area of low concentration
until equilibrium is reached.
Equilibrium is reached when
the solute is the same
throughout
Diffusion does not require
energy
Osmosis
The diffusion of water
molecules through a
biological membrane
Naturally moves from a
higher concentration to a
lower concentration
Will continue until Equilibrium
is reached
Does not require energy
Osmotic pressure is on the
hypertonic side of a selectively
permeable membrane
Almost all cells are hypertonic
to fresh water
Facilitated Diffusion
Diffusion that occurs through
protein channels in the cell
membrane
Each channel is specific and
allows only certain molecules
into the cell
Does not require energy
Molecules must flow from a
higher concentration to a
lower concentration
Active Transport
Molecules move against the
concentration difference and
flow from a lower
concentration to a higher
concentration
Requires energy
Examples:
Sodium - Potassium pump
Endocytosis - the process of
taking material into the cell by
means of infoldings, or
pockets, of the cell membrane
to make a vacuole
Phagocytosis - taking in large
particles by endocytosis
Exocytosis - the removal of
large amounts of material
from a vacuole that fuses
with the cell membrane
forcing it’s contents out of
the cell
Every living cell contains a
liquid interior and is
surrounded by liquid.
Cytosol - a solution of many
different substances in water
Cytoplasm = cytosol +
organelles
Cytoplasm
Cytosol + Organelles
Fills the entire cell
Made of water, salt and
organic substances, also
contains enzymes
Cytoplasm
Functions to hold
organelles, allows for
storage of chemicals, and
provides pathways for
molecular movement
(cytoplasmic streaming)
Cell Wall
Not found in all cells
Outside the cell membrane
Made of cellulose – a tough
carbohydrate fiber
Cell Wall
Porous enough to allow
water, oxygen, carbon
dioxide and some other
substances through easily
Main function is to provide
support and protection for
the cell
Nucleus
Largest organelle
Control Center
Contains DNA
Instructions for
everything that
goes on in the cell
DNA
Nucleic acid that stores
and transmits genetic
information from one
generation to another
Structure of DNA
Has to be able to carry
info from one generation to
another
Structure of DNA
That info needs to
determine characteristics
Needs to be easy to
copy
DNA is…
A long molecule made of
nucleotides
5 carbon sugar (ribose)
Phosphate group
Nitrogenous base
4 Bases
Adenine
Cytosine
Guanine
Thymine
Base order
Any sequence is possible
Base order = the coded
genetic information
Chargaffs’ rule
The amount of Adenine is
always equal to the
amount of Thymine
and
Chargaffs’ rule
The amount of Cytosine
is always equal to the
amount of Guanine
Base Pairing
Adenine will always pair
up with Thymine
Cytosine will always pair
up with Guanine
Wilkins and Franklin
Took x-ray defraction
photographs of DNA
molecules
Noticed a spiral shape
Watson and Crick
Looked at Chargaffs
research and photos by
Wilkins and Franklin
Built a 3 dimensional
model of DNA
Watson and Crick
Discovered the shape =
Double Helix (2 strands
wound around each other)
Page 294
The DNA Song
We love DNA
Made of nucleotides
Sugar, phosphate
and a base
Bonded down
one side
Adenine and thymine
Make a lovely pair
Cyotsine without guanine
Would feel very bare
Like a Ladder
Sugar and phosphate make
sides of the ladder
The bases are held together
with hydrogen bonds to make
the rungs
(C=G and A=T)
Replication
This structure explains how
DNA can be copied
Each half has the info
needed to make the other half
(complimentary strands)
Replication
Enzymes unzip the
molecule by breaking
hydrogen bonds (DNA
Polymerase)
Replication
Starts at one point and goes
along entire molecule (can go
in both directions)
Each strand serves as a
template for complementary
bases
Replication
The result is two DNA
molecules identical to each
other and to the original
molecule
Genes
Coded DNA instructions
that control production of
proteins
Sequence of bases are in
the DNA molecule
Mutations
 Changes in the DNA
sequence that affect
the genetic information
 Changes the kind of
protein made
Proteins
 Proteins are the keys to
almost everything that
living cells do
 Enzymes, growth
regulators, building
materials
Nucleolus
Makes Ribosomes
Ribosome
Assemble proteins
To make a protein
Step 1 – make RNA
What is RNA?
RNA
Required for protein
synthesis
Disposable copies of DNA
Long chains of nucleotides
Different from DNA
Sugar is ribose instead of
deoxyribose
Single strand not double
Uracil replaces thymine
3 Types
Messenger – carries copies
of DNA instructions
Ribosomal – found in the
ribosome
Transfer – transfers amino
acids to the ribosome
The RNA Song
We love RNA
Transcribed from DNA
Single stands of three kinds
M&T&R
M is the messenger
T does the transfer
R is in the ribosome
For translation to occur
RNA and DNA
Make a lovely pair
Synthesizing proteins and
Transcription
Copying part of the
nucleotide sequence of
DNA into a complementary
sequence of RNA
Transcription
Proteins are made of
chains of Amino Acids
Bases are read in groups of
three to code for different
Amino Acids
Transcription
the three letter “words”
are called codons
Transcription
the three letter “words”
are called codons
There are 64 possible
codons that can be made
with the 4 bases
Translation
The decoding of mRNA to
form a protein
(polypeptide chain)
Happens in the Ribosome
To Make a Protein
1. mRNA is transcribed from
DNA and released into
cytoplasm (transcription),
then attach to ribosome
To Make a Protein
2. tRNA brings amino acids to
the ribosome to match
codons
3. Ribosomes form peptide
bonds between amino acids
and breaks bonds between
amino acids and tRNA
To Make a Protein
4. Peptide chain continues to
grow until it hits a stop
Peptide chain continues to
grow until it hits a stop
codon that causes it to
release from the ribosome
and the mRNA molecule
To Make a Protein
 Proteins are the keys to
almost everything that
living cells do
 Enzymes, grow regulators,
building materials
Mutations
 Changes in the DNA
sequence that affect
the genetic information
 Changes the kind of
protein made
Chloroplasts & Mitochondria
 Changes sunlight into
food
 Changes food into
energy
 Create Energy
Energy
The ability to do work
All living things depend on
Energy
ATP
page 202
Figure 8-2
Adenosine Triphosphate
Used to store energy
needed for life processes
ADP
page 203
Figure 8-3
Adenosine Diphosphate
Similar in structure to ATP
but has only 2 phosphates
Phosphate groups can be
added or taken away
according to cell supply
and need
Energy stored in ATP is
released when it is
converted into ADP and 1
phosphate group
Uses for ATP in cells
Movement within the cell
organelles along microtubules
Active Transport
sodium/potassium pump
1 ATP molecule can move 3
sodiums and 2 potassiums
Glucose and ATP
Cells only keep a small amt
of ATP
Glucose can store 90x the
chemical energy of ATP
They keep larger amounts of
glucose
Glucose
more value
less mass
ATP
less value
more mass
Where does the cell get the
energy it needs?
Photosynthesis
Cellular Respiration
Where do they get it?
Autotrophs
Heterotrophs
(carnivore, herbivore,
omnivore, decomposer,
scavenger)
Photosynthesis
Page 206
Figure 8-4
The Equation
6CO2 + 6H2O = light =
C6H1206 + 6O2
Carbon dioxide + water in
the presence of light
becomes sugar and oxygen
Why do we know this?
Jan van Helmont
wanted to know if plants
grow from taking material
out of the soil
soil amount didn’t change
added water
Plants get mass from water
Hydrate of Carbohydrate
Carbo comes from Co2 in
the air (but Jan didn’t know
that yet)
Joseph Priestly
candle and oxygen
experiments
a mint plant produces
some substance that is
required for burning
Oxygen
Jan Ingenhousz
Priestly’s experiment only
works if the plant is
exposed to light
light is necessary for plants
to produce oxygen
Chlorophyll
The chief pigment in plants
reflects green light
absorbs red and blue
Light has many wavelengths
Pigments are light absorbing
molecules
Light absorbed = energy
absorbed from light
Chlorophyll absorbs light
Energy is transferred
directly to electrons in the
pigment
raises the energy levels in
these electrons
High energy
electrons make
photosynthesis
happen
Reactions of Photosynthesis
Inside a chloroplast(pg 208)
Thylakoid discs photosynthetic membranes
arranged in stacks called
grana (granum)
They contain
Chlorophyll and other
pigments
Photosystems - proteins that
capture energy form the sun
(Atp Synthase)
2 Reactions
Light Dependent
takes
place within the
Thylakoid Discs
Calvin Cycle
takes
place in the stroma
(outside thylakoid dics)
Calvin Cycle
also called
Light Independent Cycle or
Dark Cycle
Page 208 figure 8-7
They have to work together
NADPH
Nicotinamide adenine
dinucleotide phosphate
Carrier molecule
NADP+ becomes NADPH
• Energy of sunlight is
trapped in chemical form
• can be carried to chemical
reactions else where in the
cell
NADP+ becomes NADPH
• Accepts and holds 2 high
energy electrons along with
a Hydrogen ion H+
• Page 209 figure 8-8
Light Dependent Reactions
Page 211
figure 8-10
Light Dependent Drama
Light Independent Reactions
The Calvin Cycle
Read pages 212-213
Page 212 figure 8-11
Carbon Shuffle
Light Independent Reactions
The Calvin Cycle uses ATP
and NADPH from the light
dependent reactions to
produce high-energy sugars
So...
The Calvin Cycle uses 6
molecules of carbon dioxide
to produce just one 6-carbon
sugar molecule
But...
It can work steadily, night or
day, to turn out energy rich
sugars and remove carbon
dioxide from the air
And...
The plant uses sugars for
Energy (ATP)
building more complex
carbohydrates (starch,
cellulose) to be used for
growth and development
Factors Affecting Photosynthesis
Water
Temperature
Intensity of Light
Cellular Respiration
Glucose
What do we do with it?
What kind of energy does the
cell need?
ATP
We have to break down
the glucose so that it
can be used by the
cell.
Glycolysis
Quick production of ATP and
NADH for cellular energy
Releases only a small
amount of energy
The process in which 1
molecule of glucose is
broken in half, producing 2
molecules of pyruvic acid
(a 3 carbon compound)
Net production of 2 ATP
molecules
If Oxygen is present,
Glycolysis leads to the Krebs
cycle and the Electron
Transport Chain (Aerobic)
If Oxygen is not present,
Glycolysis leads to the
Fermentation
(Anaerobic)
2 Kinds of Fermentation
Lactic Acid which produces
lactic acid and 2NAD+
Alcoholic which produces
alcohol, 2NAD+ and CO2
Without oxygen, Glycoysis
and Fermentation can make
small amounts of ATP
quickly, by working together
Fermentation Lab
If Oxygen is present,
glycolysis leads to the Krebs
cycle and the electron
transport chain
Krebs Cycle
CO2 is given off (exhaled)
High energy carriers have to
be passed to the Electron
Transport Chain where ADP
can be converted to ATP
Electron Transport Chain
NADH goes to NAD+
FADH goes to FAD
ADP goes to ATP
The Totals
Glycolysis makes 2 ATP
molecules
Krebs cycle and ETC make
34 ATP molecules
Total = 36 molecules of ATP
In the presence of oxygen,
Glycolysis, the Kreb Cycle
and the Electron Transport
Chain function to provide
long term, slow production
of ATP for cellular use.