Transcript Unit 1 – Life on Earth

1.
Cell Ultrastructure
2.
Transport Across The
Membrane
3.
Cell division
4.
DNA & Protein Production
5.
Enzymes
6.
Genetic Engineering
7.
Photosynthesis
8.
Respiration
Topic 1
Cell Functions and Structures
Structure
Function
Cell Type
Nucleus
Controls cell activities
All
Cytoplasm
Site of chemical reactions
All
Cell Membrane Controls exchange of materials in/out
of the cell
TASK!
All
Ribosomes
All
Mitochondria
Site of protein
synthesis
Make
Match
Cards of the
Site
of Aerobic Respiration
(ATP/
structures
and functions.
Chloroplasts
Site of photosynthesis
Green Plants
Vacuole
Stores cell sap
Plant, Fungal
Cell Wall
Provides structure and prevents
bursting
Plant, Fungal,
Bacteria
Plasmid
Extra ring of DNA
Bacteria
Energy Production)
All
Fungal Cell
Bacterial Cell
3D Model Homework
Choose 1 of the 4 cell types and
create a 3D model with structures
clearly labelled.
Model is due 1 week today.
Topic 2
Transport: Key Terms and Definitions
Term
Definition
Passive Transport
Movement of molecules without using ATP (energy)
Diffusion
The movement of molecules from an area of high
concentration to an area of low concentration down a
concentration gradient
Osmosis
TASK
The movement of water molecules from an area of
Makehigh
Match
Cards
ofarea
these
concentration
to an
of low concentration
a concentration
gradient
key down
terms
and definitions.
Active Transport
The movement of molecules from an area of low
concentration to an area of high concentration
against a concentration gradient using ATP (energy)
Hypertonic
A solution which has a lower water concentration to
that of the cell contents
Isotonic
A solution which has equal water concentration to
that of the cells contents
Hypotonic
A solution which has greater water concentration to
that of the cell contents.
Structure of the Cell Membrane
• The
cell membrane is made of PROTEINS and LIPID molecules
in a BI-LAYER known as the fluid mosaic model.
TASK
Use the worksheet
provided to create your
own model membrane.
• Proteins
are spaced randomly and can be embedded or span the
entire width of the membrane.
• These
proteins can be CARRIERS during active transport or
create protein CHANNELS/PORES for passive transport
processes.
Passive Transport: Diffusion
• Diffusion
is the passive transport of molecules from an area of
high concentration to an area of low concentration down a
concentration gradient.Experiment 1
does not
require
any energy
as molecules
Using
visking
tubing
as a which are
small enough will pass
through
protein channels
in/out of the
model
membrane
show
cell as required.
• Diffusion
• Examples
that only small molecules
of molecules which move by this transport method
can Dioxide
pass through.
include: Oxygen, Carbon
and Glucose.
Passive Transport: Osmosis
• Osmosis
is a special case of diffusion as it refers solely
to the movement of WATER.
• Osmosis
is the movement of water molecules from an
area of high water concentration to an area of low
water concentration down a concentration gradient.
• Osmosis
occurs continually to maintain balance in
organisms as too much or too little water can have a
detrimental effect on the cell.
Osmotic Effects on Cells
THINK! What
do you think
each of the
terms isotonic,
hypotonic and
hypertonic
mean in this
context? Use
the diagrams
to help you and
discuss with
your partner.
Experiment 2
Using identical cylinders
of potato and various
concentrations of salt,
identify the ISOTONIC
water concentration in
plant tissue.
Active Transport
• Active
transport involves the embedded protein
molecules in the fluid membrane acting as carrier
molecules to transport larger molecules across the
membrane.
• Active transport requires energy (ATP) as molecules
are moved AGAINST a concentration gradient from a
high concentration to a low concentration.
• Examples of substances that enter a cell by active
transport include ions such as Sodium and Potassium.
Topic 3
Cell Division: Mitosis
• MITOSIS
is the term given to the process of
cell division.
• Cells must divide for GROWTH and REPAIR
purposes in the body.
• There are 6 key stages in this process which
ends in 2 daughter cells being IDENTICAL to
the parent cell.
• They are genetically identical to prevent loss
of information (sometimes written as
maintaining the cells chromosome complement)
Stage
Description
1
Chromosomes become visible after
undergoing DNA replication
2
3
4
Chromosomes shorten and pair up as
TASK
TASK
chromatids
Makethe
Picture
and
Description
Use
resources
provided to
match
cards.of
Nuclear
membrane
draw out the
6 stages
Mitosis.disappears and
chromatidsexam
line up at the cells
Mitosis is a favourite
equator
question so you
must know
EVERYSpindle
stage.fibres pull apart
chromosomes to opposite poles in
the cell
5
Nuclear membrane forms around
groups of chromosomes and
cytoplasm divides
6
2 identical daughter cells formed
Cell Culturing
• Cells
can be grown in lab cultures for use in research or
classroom practice.
• In order for any cell culture to be grown, the right
growing conditions must be present;
- Nutrient growth medium
- Optimum pH
- Optimum temperature
• Cell
cultures can be grown on a
variety of mediums including:
- Agar plates
- Agar slopes
- Agar broths
Aseptic Techniques
• Aseptic
techniques are used
for all cell culturing
experiment to AVOID
CONTAMINATION.
• Aseptic
techniques and
conditions ensure sterile
conditions as far as possible.
• Aseptic
-
conditions include:
Hand washing
Hair tied back
Apron/Lab Coat
Working close to a flame
Disinfecting work area
Flaming bottle neck/
metal loop
Cell Culturing
• When streaking an agar
plate to grow a cell culture
you must follow the zig zag
pattern as shown on the
Experiment 3
image.
Use your knowledge of
aseptic
• The initial streak
will betechniques to
culture
very dense with
your yeast on an agar
microbe so by streaking plate.
it
out a further 3 times you
can identify a single colony
to transfer for growth.
THINK! What do you
notice about the edge of
each zig zag? Why do
you think this is done?
Topic 4
Deoxyribonucleic Acid (DNA)
• D.N.A
is found inside the
nucleus of a cell on
threadlike structures
called chromosomes.
• D.N.A.
has a unique
structure in that it
consists of a 2 strands
twisted together known as
a double stranded helix.
EXAM Favourite
DNA questions often come
up as problem solving
questions.
Nucleotides
• D.N.A
is made up of repeating units called NUCLEOTIDES.
• Nucleotides
are made up of a phosphate, a ribose sugar and 1
TASK
TASK
Use
Use
the
the
model
sweets
kitsprovided
in pairs to
to
• The 4 bases are;
create aanmodel
edibleofDNA
the DNA
helix.
- Adenosine create
Ensure
andyou
complementary
have the bases
base
in
- Thymine helix
- Cytosine complimentary
pairs.
fashion and can
- Guanine
explain the structure. Take a
• The bases aresmiling
COMPLIMENTARY
always pairing with
selfie with with
yourAmodel
T and G always pairing
withyou
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before
of 4 bases.
Proteins
• The
order of the bases on a DNA strand provide a
specific code for a particular type of protein to be made
at the ribosome.
• Examples
table:
of proteins and their functions are given in the
Protein
Function
Enzyme
Speeds up chemical reactions
Hormone
Carries signals to target tissues
from another area of the body to
bring about an appropriate
response.
Antibody
Fights off infection/ foreign
pathogens in the body
Making Proteins
• Stage
1: Free nucleotides in the
nucleus of the cell make a copy of the
coding region on DNA. This single
stranded molecule contains the
blueprint instructions for making the
protein and is called messenger RNA
(mRNA).
• Stage
2: mRNA leaves the nucleus
through pores and into the cytoplasm
to a ribosome.
• Stage
3: The ribosome reads 3 bases
(called a codon) at a time and brings
the amino acid associated with that
codon into position to form a
polypeptide chain.
• Stage
4: This chain of amino acids is
then folded into shape to form the
new protein.
Topic 5
What Are Enzymes?
• Enzymes
are BIOLOGICAL CATALYSTS found in all living
organisms that:
- speed up (or in some cases slow down) chemical reactions .
- lower the activation energy required for the reaction to
occur.
- remain unchanged in the reaction.
- are SPECIFIC.
• Enzymes
are protein molecules which have a structure suited to
fit only one substrate molecule. This area which fits the
substrate is called the ACTIVE SITE and ensures
SPECIFICITY is achieved
(lock and key theory).
Enzyme Activity and Examples
• Enzyme activity is greatest in the enzymes OPTIMUM
conditions such as theExperiment
right temperature
and pH.
Experiment
65
Experiment
74
Experiment
Show that
enzyme
Investigate
how
enzyme
Investigating
which
fruit
Investigating
enzyme
• Anything belowactivity
this will
slow be
activity
reactions
can
be and anything above will
can
affected
has
the
greatest
content
SPECIFICITY
usingsite becoming
stop activity entirely
due to thereactions
active
SYNTHESIS
by temperature
and pH
of
the
enzyme
the
enzyme
misshapen. This is when
anthe
enzyme
DENATURES.
using
enzyme
using
the
enzyme
CATALASE.
AMYLASE.
PHOSPHORYLASE.
AMYLASE.
• There are two types of enzyme reactions: SYNTHESIS
DEGRADATION
•
Substrate
Enzyme
Product
Starch
Amylase
Maltose
Fats
Lipase
Fatty Acids and
Glycerol
Hydrogen Peroxide
Catalase
Water and Oxygen
Enzyme Activity Graphs
Enzymes Assignment
• You
will now be asked to write an assignment on the use
of ENZYMES.
• You will be asked to write this in EXAM CONDITIONS
IN CLASS.
• It is essential that you:
- Have a clear aim
- Have a minimum word count of 500
- Have two different sources (1 exp. & 1 other)
- Process your sources into 2 different formats (tables
to graphs)
- Compare your sources
- Can make a conclusion about your aim USING the info
from your
2 sources.
• RAW data i.e. line graph from source 1, MUST have
gridlines and have the FULL URL or reference for it.
Topic 6
Genetic Engineering
• Genetic
engineering is the process of ARTIFICIALLY
altering the genome (Genetic make-up) of a cell.
• Scientists use genetic engineering to alter a bacterial
plasmid to produce useful substances QUICKLY.
• 2 substances which are produced in this manner are :
- Human Growth Hormone (HGH)
- Insulin
THINK! What do each of these substances treat?
What other benefits are there of using Genetic
Engineering to manufacture these substances?
EXAM Favourite
Stages of Genetic Engineering are always
asked.
Make sure you can identify each stage
AND describe what is happening. You might
want to make your own match cards to help
with this.
Genetically Modifying Organisms
Has Science
gone too far??
Research GM
Crops on the
iPads
Topic 7
What is Photosynthesis?
• Photosynthesis
is the process which green plants undergo
to create their own food using light energy.
• Water and Carbon Dioxide are the RAW materials.
• Glucose and Oxygen are the PRODUCTS.
• Photosynthesis happens in two stages:
1. Light Dependant Reaction (occurs in the grana of
the chloroplasts)
2. Carbon Fixation (occurs in the stroma of the
chloroplasts)
Light
Water + Carbon Dioxide
Glucose + Oxygen
Chlorophyll
Stage 1: Light Dependant
• Water
is absorbed into the plant
by the roots.
• Light energy trapped in the grana
is used to SPLIT water into
Oxygen and Hydrogen.
• Oxygen is a WASTE product to
plants and is released into the
atmosphere through tiny pores
called stomata.
• Hydrogen is required for Stage
2 and is moved by a carrier into
the Stroma.
• ATP is also generated in this
stage for use in Stage 2.
Stage 2: Carbon Fixation
• Carbon
Dioxide enters the
plant from the atmosphere
through the stomata.
• The
ATP (energy) from
stage 1 is used in a reaction
to join the Carbon dioxide
to the Hydrogen (again from
stage 1) to form a sugar
called GLUCOSE.
• Photosynthesis
is an
ENZYME CONTROLLED
reaction and is therefore
affected by temperatures
out with an enzymes
optimum.
Fates of Glucose
• The
glucose which is made during
photosynthesis can be used by the plant in any
1 of the following 3 ways
• Firstly it can be used straight away as ENERGY
• Secondly it can be converted to CELLULOSE for
the structural purpose of the cell wall.
• Finally it can be converted to the storage
carbohydrate STARCH.
Limiting Factors of Photosynthesis
•
There are 3 limiting factors associated with the RATE of
photosynthesis.
1. Carbon Dioxide Concentration
Experiment 7
2. Light Intensity
TASK
3. Temperature
Test a leaf for starch in
• Limiting
Practice naming the
limiting factors from
prove that •certain
Anytime
a point is on the
the graphs drawn
on the
factors can limitinitial
glucose
INCLINE the limiting
board. factor is always what is
production.
factor questions
always
involve graphs
various
conditions
toas shown below:
written on the horizontal
axis.
• If a point is on the straight
level-off line, then the factor
limiting the photosynthesis is
any of the other 2.
Topic 7
What is Respiration?
• Respiration
is the process by which 1 molecule of glucose
is broken down in the body to release ATP (energy)
Glucose + Oxygen
• There
Carbon Dioxide + Water (+ENERGY)
are 2 pathways for respiration:
1. AEROBIC (with Oxygen)
2. FERMENTATION (Without Oxygen)
THINK! Do you notice anything about
the Respiration equation?
Linking Systems in Plants
Understanding ATP
• ATP
is a high energy compound made of 1 Adenosine and
3 inorganic phosphate molecules.
• The energy is stored in the third bond between the last
2 phosphates. When this bond is broken the energy is
released forming the molecule ADP+Pi.
Aerobic Respiration
GLUCOSE
2 ATP
4 ATP
There is a
NET GAIN
of 2 ATP
2x Pyruvic Acid
• Aerobic
Respiration occurs in
two stages. The first stage is
called GLYCOLOSIS and occurs
in the CYTOPLASM.
• Glucose is SPLIT into 2
molecules of Pyruvic Acid.
• ATP (energy) has to be used to
start this reaction, however
the release of 4 ATP means
that there is a NET GAIN of
2 ATP
• No Oxygen is required for this
stage to occur, therefore
common to both Aerobic and
Fermentation pathways .
Aerobic Respiration Cont’d
• The
second stage of Aerobic
respiration occurs in the
MITOCHONDRIA and can only
occur in the presence of
oxygen.
Pyruvate
36
ATP
Made
• The
2 Pyruvate molecules
undergo a series of chemical
reactions to release CARBON
DIOXIDE as waste.
• HYDROGEN
is also released
during this stage and is
COMBINED with OXYGEN
using the ATP to form water.
is described as the last
Hydrogen ACCEPTOR in this
chain of events.
Carbon
Dioxide
Hydrogen
• Oxygen
Oxygen
Water
Fermentation
•
The second pathway in respiration is called FERMENTATION and
occurs in the absence of oxygen.
• In
animals, when there is a lack of
Oxygen for complete breakdown of
glucose the pyruvate is converted into a
substance called LACTIC ACID.
• Lactic
Acid builds up in muscles causing
fatigue.
• When
oxygen is available once again, the
lactic acid is converted back into
pyruvate for the aerobic cycle to
continue.
• We
say that an OXYGEN DEBT has been
paid.
Fermentation
• In
plants/fungi etc, when there is a
lack of oxygen for complete breakdown
of glucose the pyruvate is
converted 8
Experiment
into ethanol and carbon dioxide.
Investigate how carbon dioxide
produced in fermentation of yeast can
• This process is completely
irreversible.be useful in the baking industry.
• We
can use fermentation to our
advantage in certain industries such as
brewing and baking.
THINK! Why do you not
taste alcohol in bakery
products such as bread and
cakes?