Download Unit 2: Multi-cellular organisms

Charleston Academy
Biology National 5
Unit 1: Cell Biology
Revision: What you should know
(From Torrance (2013) National 5 Biology)
Key Areas 1 and 2
Cell Structure and Transport
Word bank
active
against
along
animal
burst
cells
chloroplasts
concentration
diffusion
energy
gain
gradient
lipid
lose
lower
membrane
mitochondria
nucleus
osmosis
passive
permeable
plasmolysed
ribosomes
sap
selectively
shrink
supported
useful
vacuole
walls
1.
All living things are composed of one or more CELLS, the basic units of life.
2.
The cells of green plants, animals and fungi have several structures in common
including a NUCLEUS, a cell MEMBRANE and mitochondria.
3.
ANIMAL cells lack a cell wall and a large central VACUOLE.
4.
Only green plant cells contain CHLOROPLASTS but all cells contain ribosomes.
5.
The cell’s activities are controlled by the nucleus. A plant cell is SUPPORTED
by the cell wall and its cell SAP is stored in its vacuole.
6.
Chloroplasts are responsible for photosynthesis, MITOCHONDRIA for
respiration and RIBOSOMES for protein synthesis.
7.
The cell membrane consists of protein and LIPID molecules and is
SELECTIVELY permeable.
8.
Diffusion is the movement of molecules from a high to a low concentration
ALONG a concentration GRADIENT. It is a PASSIVE process and does not
require a supply of energy.
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9.
DIFFUSION is the means by which USEFUL molecules enter and waste
materials leave a cell.
10. OSMOSIS is a special case of diffusion during which water molecules move
along a water CONCENTRATION gradient from a region of higher water
concentration to a region of LOWER water concentration through a selectively
PERMEABLE membrane.
11.
When placed in a solution with a water concentration higher than that of their
cell contents, cells GAIN water by osmosis. Animal cells swell up and may
BURST; plant cells also swell up but are prevented from bursting by their cell
WALLS.
12. When placed in a solution with a water concentration lower than that of their
cell contents, cells LOSE water by osmosis. Animal cells SHRINK and plant
cells become PLASMOLYSED.
13. Ions and molecules of some chemical substances are actively transported
across the cell membrane AGAINST a concentration gradient.
14. ACTIVE transport is brought about by membrane protein molecules and
requires ENERGY.
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Key Areas 3-6
Cell Division
DNA and Proteins
Proteins and Enzymes
Genetic Engineering
Word bank
1.
active
amino
antibodies
aseptic
base
benefit
catalyst
centromere
chromatids
chromosome
chromosome
code
complement
complementary
contaminating
denatured
diploid
DNA
DNA
energy
engineering
enzymes
equator
fibre
function
gene
genetic
helix
host
inserted
medium
mitosis
modified
nucleus
optimum
optimum
plasmid
products
protein
protein
ribosome
RNA
sequence
sequence
shape
site
structural
substrate
temperature
unaltered
wall
During cell division, the NUCLEUS divides first, followed by the cytoplasm. In
a plant cell, a new cell WALL is laid down between the two daughter cells
formed.
2.
Every species has a characteristic number of chromosomes called its
chromosome COMPLEMENT. Normally this takes the form of two matching
sets of chromosomes and the cell that contains them is said to be DIPLOID.
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3.
The process by which the nucleus of a diploid cell divides into two nuclei, each
of which receives a copy of the diploid CHROMOSOME complement, is called
MITOSIS.
4.
During mitosis each chromosome, consisting of two identical CHROMATIDS,
becomes attached by its CENTROMERE to a spindle FIBRE at the cell’s
EQUATOR. One chromatid from each chromosome moves to the north pole
and one to the south pole forming two nuclei.
5.
During culturing of cells, ASEPTIC techniques are employed to prevent
unwanted spores CONTAMINATING the cultures.
6.
In order to grow, cells in a culture need an appropriate MEDIUM containing
nutrients that provide ENERGY and a supply of cell-building materials. They
also require an environment where all factors are controlled and maintained at
OPTIMUM levels.
7.
Chromosomes contain DNA. A molecule of DNA consists of two strands coiled
into a double-stranded HELIX. The two strands are held together by weak
bonds between their bases. There are four types of base. A pairs with T and
G pairs with C to form complementary BASE pairs.
8.
Information called the genetic CODE is present in DNA. It takes the form of
codewords of bases that correspond to AMINO acids, the building blocks of
proteins.
9.
The sequence of bases in DNA determines the SEQUENCE in which amino
acids are assembled in a PROTEIN.
10. The genetic code for a protein, present on DNA is carried by messenger RNA
from the nucleus to a RIBOSOME in the cytoplasm where the appropriate
amino acids become joined together into the protein.
11.
Both the shape and FUNCTION of a protein molecule are determined by the
particular SEQUENCE of amino acids that make up the PROTEIN.
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12. Some proteins have a STRUCTURAL function; others act as hormones,
ANTIBODIES or enzymes.
13. A CATALYST is a substance that speeds up the rate of a chemical reaction
but remains UNALTERED by the reaction. ENZYMES are biological catalysts
produced by all living cells.
14. The shape of the ACTIVE site on an enzyme molecule is COMPLEMENTARY to
the molecular structure of its SUBSTRATE, allowing them to combine
together closely.
15. Following catalytic activity, the end PRODUCTS become detached from the
active SITE, leaving the enzyme unchanged.
16. To function efficiently, an enzyme needs an appropriate pH and a suitable
TEMPERATURE. Each enzyme works best in its OPTIMUM conditions. At
temperatures above 55oC, most enzyme molecules are inactive because their
molecular SHAPE has been irreversibly altered. They are described as being
DENATURED.
17. DNA can be transferred naturally from one cell to another. DNA can also be
transferred by genetic ENGINEERING.
18. During GENETIC engineering, the section of DNA that contains the required
GENE is identified and cut out of the source CHROMOSOME. Then the gene
is inserted into a vector such as a bacterial PLASMID.
19. The reprogrammed plasmid is INSERTED into a HOST cell such as a
bacterium.
20. The transformed host cell (now a genetically MODIFIED organism) grows and
multiplies and provides humans with some BENEFIT.
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Key Areas 7 and 8
Photosynthesis
Respiration
Word bank
1.
ADP
aerobic
ATP
cellular
cellulose
chlorophyll
cytoplasm
dioxide
energy
enzymes
ethanol
fermentation
fixation
glucose
hydrogen
intensity
lactic
light
limited
mitochondria
oxygen
photosynthesis
pyruvate
regenerate
respiration
split
temperature
thirty-eight
two
water
The chemical ENERGY stored in glucose is released by a series of reactions
controlled by ENZYMES. This biochemical process is called RESPIRATION.
2.
ATP is a high-energy compound that can be broken down to ADP and
phosphate. This process releases the energy required for CELLULAR
processes.
3.
ATP is regenerated from ADP and phosphate using energy released during
respiration.
4.
The first stage of the respiratory pathway is common to both AEROBIC
respiration and
fermentation (anaerobic respiration). It involves
the
breakdown of glucose to PYRUVATE.
5.
In the presence of OXYGEN, aerobic respiration occurs. WATER and carbon
dioxide are formed and THIRTY-EIGHT molecules of ATP are produced per
molecule of glucose.
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6.
In the absence of oxygen, FERMENTATION occurs. In animal cells, pyruvate
is reversibly converted to LACTIC acid. In plant cells, pyruvate is irreversibly
converted to ETHANOL and carbon dioxide. In each case only TWO molecules
of ATP are produced per molecule of glucose.
7.
Aerobic respiration begins in a cell’s cytoplasm and is completed in its
MITOCHONDRIA. Fermentation occurs in the CYTOPLASM only.
8.
Green plants use LIGHT as their source of energy to make food. This process
is called PHOTOSYNTHESIS. It is a two-stage process.
9.
During the first stage, which is made up of light reactions, light energy is
captured by green CHLOROPHYLL in chloroplasts. Some energy is used to
REGENERATE ATP from ADP and phosphate. Some energy is used to SPLIT
water into oxygen and HYDROGEN.
10. During the second stage of photosynthesis, called carbon FIXATION,
hydrogen produced during the first stage is combined with carbon DIOXIDE
to form glucose. This process requires energy, which is supplied by ATP.
11.
Some GLUCOSE molecules produced by photosynthesis are used in cellular
respiration; others are converted to products such as starch and CELLULOSE.
12. Photosynthesis
is
affected
by
environmental
factors
such
as
light
INTENSITY, carbon dioxide concentration and TEMPERATURE. Its rate is
therefore LIMITED by whichever one of these factors is in short supply.
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