Macromolecules. Chromosomes are made up of genes. DNA and protein synthesis. Structure and function of protein molecules in cells

THEME ONE Macromolecules Threads Organisation Selectivity Energy Flow Perpetuation Evolution Human Awareness Worksheets 1 The structure of DNA 2 ...
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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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