THEME
ONE
Macromolecules
Threads
Organisation
Selectivity
Energy Flow
Perpetuation
Evolution
Human Awareness
Worksheets
1
The structure of DNA
2
Chromosomes are made up of genes
3
DNA and protein synthesis
4
Structure and function of protein molecules in cells
5
The importance of polysaccharides and lipids
6
DNA replication
7
Enzymes
8
DNA and protein evidence for evolution
9
Mutations
10 Genetic manipulation
11 Some social consequences of genetic manipulation
12 Multiplying and sequencing DNA
Key Ideas
Students should know and understand the following
M1
The chemical unit of genetic information in most organisms in DNA
M2
The structural unit of information in the cell is the chromosome
M3
The functional unit of information on the chromosome is the gene
M4
The flow of information from DNA to prtein is unidirectional in most organisms
DNA →RNA →protein
M5
The three-dimensional structure of protein is critical to its function
M6
Polysaccharides and lipids are important macromolecules in cells and organisms
M7
Specific base-pairing is the mechanism of DNA replication
M8
Enzymes are specific for their substrate
M9
Molecular recognition is an important property for life processes
M10
Enzymes increase reaction rates by lowering activation energy
M11
Macromolecules are used as energy reserves
M12
DNA carries genetic information from one generation to the next
M13
The universal presence of DNA is strong evidence for the common ancestry of all living things
M14
DNA and protein sequences usually show greater similarity between closely related groups of
organisms than between distantly related groups
M15
Change in the base sequence of DNA can lead to the alteration of absence of proteins, and to th
appearance of new characteristics in the descendants
M16
Human beings can manipulate DNA
M17
Human beings can sequence even small amounts of DNA
© SACE 2013
MACROMOLECULES
BIOLOGY ESSENTIALS STAGE 2
Worksheet 1 Structure of DNA
DNA stands for ‘deoxyribonucleic acid’. This molecule is found primarily in the nucleus of cells. It is a double
stranded molecule with the strands wound around each other to form a double helix. The molecule is made up
of repeating units called nucleotides. A single nucleotide is made up of three components: a deoxyribose sugar, a
phosphate and an organic base.
The diagram below is a representation of 2 nucleotides bonded together.
Bases
A
T
Deoxyribose
sugar
Phosphate
Weak hydrogen bonds between bases
There are four organic bases found in DNA: Adenine, Thymine, Guanine and Cytosine. The
letters A, T, G and C represent these bases.
A single strand of DNA is a sequence of nucleotides joined together with alternating
phosphate and sugar components. The double helix molecule consists of two
complementary strands that are joined by hydrogen bonds between the bases.
The bases always pair in specific ways:
Adenine always bonds with Thymine
Guanine always bonds with Cytosine
Thymine always bonds with Adenine
Cytosine always bonds with Guanine
A
T
A
G
C
C
C
T
G
G
A
T
C
G
A
T
A
T
G
A
xercises
1.
T
A
The adjacent diagram shows the double helical model for DNA first proposed by two scientists
Watson and Crick in 1953.
••E
C
G
C
T
Write a concise statement to explain each of the following terms:
complementary
DNA
macromolecule
monomer
nucleic acid
nucleotide
organic
polymer
base
deoxyribose
phosphate
4
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DESCRIPTION
PHYSICS
TOPPHYSICS
DETAIL
OF UNIFORM
HERE
OF PROJECTILE
CIRCULAR
MOTION
StructureMOTION
of DNA
The following sequence of bases was found in a segment of DNA
A A G G C T T G C
3.
Name the four major organic bases found in DNA.
macromolecules
2.
WORKSHEET 1
Write the sequence of bases that would be found in the complementary strand.
4.
Write down the four possible base pairings in DNA.
5.
If a sequence of DNA has 30% guanine bases in it what percentage of thymine would there be?
6.
Refer to the diagram below.
Sugar
Base
Phosphate
Sugar
Phosphate
Sugar
Phosphate
Base
Base
(a) Circle a nucleotide in the representation of a strand of DNA shown above.
(b) How many nucleotides are shown in the diagram?
7.
Use the figure to label A B C and D in the diagram below.
Sugar
Phosphate
Base
A
A
T
B
C
D
A
B
C
D
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5
MACROMOLECULES
BIOLOGY ESSENTIALS STAGE 2
WORKSHEET 1 SAMPLE EXAM QUESTIONS
SECTION A: MULTIPLE-CHOICE QUESTIONS
1.
Referring to the structure of DNA which one of the following statements is true?
J
The number of cytosine molecules is the same as the number of thymine molecules
K
The number of sugar molecules is the same as the number of phosphate molecules
L
The number of nitrogen bases is twice the number of sugar molecules
M
The number of adenine molecules is the same as the number of guanine molecules
2.
How many thymine molecules are present in a DNA molecule of 3000 bases if 30% of the base molecules are Guanine?
J
K
L
M
3.
Refer to the diagram below of a molecule of DNA on which a molecule of mRNA is being synthesized to answer the question that follows.
900
1200
400
600
A
DNA molecule
What does component A represent?
J
K
L
M
6
RNA molecule
Phosphate
Uracil
Nitrogen base
Ribose sugar
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DESCRIPTION
PHYSICS
TOPPHYSICS
DETAIL
OF UNIFORM
HERE
OF PROJECTILE
CIRCULAR
MOTION
StructureMOTION
of DNA
WORKSHEET 1
4.
Refer to the diagram below where A and B represent nitrogenous bases that bind together in a complementary manner. Use this information to answer the questions that follow
(a) Name structures X
Y
(b) macromolecules
SECTION B: SHORT-ANSWER QUESTIONS
(2 marks)
Explain an advantage to the cell of having A and B held together by weak hydrogen bonds that can easily be broken apart and later re-formed.
(4 marks)
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7
MACROMOLECULES
BIOLOGY ESSENTIALS STAGE 2
Worksheet 2 Chromosomes and genes
Chromosomes are thread-like structures made up of DNA and proteins call histones. These structures are found
in the nucleus of eukaryotic cells and are visible as the cells start to divide. The chromosome number is constant
for each species, e.g. 46 in humans, 48 in a chimpanzee, 40 in a mouse and 38 in cabbage. Chromosomes in nondividing cells are single stranded and the DNA is not condensed, that is, the DNA is spread out to make it easier to
access genes in transcription, an important process in protein synthesis and replication, where another copy of the
DNA is made. When the chromosomes are visible during the Prophase stage of mitosis and/or meiosis they appear
double stranded. This doubling has occurred as the DNA has replicated in order that new cells can receive their
complement of DNA.
A gene is the unit of heredity. Genes represent sequences of the bases A T G and C on chromosomes and code
for protein molecules or parts of protein molecules called polypeptide chains. Each gene is found on a particular
chromosome. Genes prescribe the features of an organism: green eyes, skin colour or the shape of a nose. In a
human with 46 chromosomes it is thought that there are around 25,000 genes, each chromosome containing
hundreds or thousands of genes.
A single gene usually contains between 300 to several thousand bases. Each gene has a start and a finish to signal
where transcription begins and ends.
The diagram below shows schematic representations of some human chromosomes and some of the gene locations that
have been identified.
The Human Genome Project (HGP)
This is a project that was first proposed around 1987. Its aim was to map the entire sequence of genes to
chromosomes and sequence the human genome. The adjacent figure illustrates some of the known gene
locations (loci). In Adelaide a group of scientists at the Women and Children's Hospital was involved in studying
chromosome 16. This overall mapping was a major undertaking as there are approximately 3 billion building
blocks or nucleotides in the total genome. This project was completed in 1983 and research continues into how this
information can be best used, particularly in medicine.
2
3
Familial
Retinitis
Colon Cancer Pigmentosa
7
9
11
12
Cystic
Fibrosis
Malignant
Melanoma
Sickle-cell
Anemia
PKU
14
Alzheimer's
Disease
17
Breast
Cancer
This photograph shows a typical set of human chromosomes,
which was taken from a prepared slide using a light microscope.
The images have been cut out and pasted together to show the
homologous pairs. Until recently this was done with scissors,
it is now done with computer software They are generally
numbered and arranged from longest to shortest.
The sex chromosomes are bottom right of this photo.
This is the male set of chromosomes or karyotype. A female has
two copies of the longer (X) sex chromosome
instead of one long (X) and one short (Y).
8
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DESCRIPTION
PHYSICS
TOPPHYSICS
DETAIL
OF UNIFORM
HERE
OF PROJECTILE
CIRCULAR
MOTION
MOTION
Chromosomes
and
genes
WORKSHEET 2
••E
xercises
macromolecules
1.
Write a concise statement to explain each of the following terms:
chromatid
chromosome
gene
genome
2.
In what organelle are the chromosomes found in eukaryotic cells?
3.
Why are the chromosomes not usually visible in non-dividing cells?
4.
Explain the differences between DNA, genes, chromosomes.
5.
What does it mean to say that a gene is linked to a chromosome?
6.
Explain the significance of different species having different numbers and types of chromosomes?
7.
Approximately how many genes are there;
(a) on one human chromosome? (b) in the human genome? 8.
Explain what it means to say that the structural unit of information in an organism is the chromosome.
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9
MACROMOLECULES
BIOLOGY ESSENTIALS STAGE 2
WORKSHEET 2 SAMPLE EXAM QUESTIONS
Exam questions on this topic are very limited as most of the concepts are tested when linked with others
developed later in the course. Instead we have included a question based on the practical component of the
course.
SECTION B: SHORT-ANSWER (PRACTICAL) QUESTIONS
1.Catalase is an enzyme found in most living tissue that releases oxygen from hydrogen peroxide.
Four groups of students investigated the effect of increasing the temperature on the activity of
catalase on some fresh liver tissue.
The results are shown in the table below
Group
Volume of oxygen (cm3) collected in 3 minutes
Temperature (°C)
5
10
20
30
40
50
1
8
16
24
32
58
27
2
7
13
26
41
62
13
3
6
12
26
20
41
28
4
4
14
22
37
49
19
Average
6
14
25
33
53
22
(a) In this space provided draw and fully label a graph of the average data to represent the effect of
temperature on the rate of catalase activity.
(6 marks)
10
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DESCRIPTION
PHYSICS
TOPPHYSICS
DETAIL
OF UNIFORM
HERE
OF PROJECTILE
CIRCULAR
MOTION
MOTION
Chromosomes
and
genes
(b) WORKSHEET 2
State a hypothesis that could be tested here.
(c)
What is the independent variable?
(2 marks)
(d)
What is the dependent variable?
(e)
What is one other variable that must be controlled?
(2 marks)
(2 marks)
(f) Describe one random error that may have given rise to some inaccurate data in this experiment.
(2 marks)
(g) Describe the pattern of results observed from the data
(4 marks)
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11
macromolecules
(2 marks)
MACROMOLECULES
BIOLOGY ESSENTIALS STAGE 2
Worksheet 3 DNA replication
DNA is the molecule of life. It has already been established that DNA is a double stranded molecule that
forms a helical structure. It is like a ladder with two sides that are held together by hydrogen bonds between
complementary base pairs. When cells divide by either mitosis or meiosis it is necessary to replicate or make other
copies of the DNA so that it can be passed on to the daughter cells.
This process of DNA replication is achieved by the complementary base pairings.
Adenine bonds to Thymine and Guanine bonds to Cytosine. The process is termed semi-conservative replication.
Each DNA molecule made consists of one old strand and one new strand.
The diagram below shows the process of DNA replication. This process occurs in the nucleus of a cell.
In this process the original DNA unzips exposing the DNA bases. DNA nucleotides that are floating free in the
nucleus, link in a complementary manner with the help of the enzyme DNA polymerase to form the two new
strands.
Original DNA
A
T
C
G
T
C
A
G
T
TA
T
T A
C
C
C
G
C
C
G
C
G
A
T
G
G
TA
TA
New Strand
TA
A
T
A
T
C
G
G
TA
C
T
A
T
TA
A
G
G C
C
A T
G
C
New Strand
Chromosomes in cells are made up of one thread; following replication, each chromosome consists of two threads
called chromatids that are joined at the centromere.
Each molecule of DNA contains one ‘old’ strand and one ‘new’ strand and this is why the process is sometimes
called ‘semi-conservative’.
Two identical
chromatids
The diagrams illustrate what happens to the chromosomes
during the process of DNA replication.
centromere
12
Semi-conservative
replication
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