DNA: the code of life

Question 1

Full name of DNA

Answer 1

Deoxyribonucleic acid

Question 2

Organisms with no nucleus

Answer 2

prokaryotes e.g. bacteria

Question 3

Location of DNA in eukaryotes

Answer 3

Nucleus

Also in:

• Mitochondria in plants and animals
• Chloroplasts in plants

Question 4

Examples of eukaryotic kingdoms

Answer 4

• plants
• animals
• fungi
• protists

Question 5

DNA and proteins forming a dense network of fibres in the nucleus

Answer 5

Chromatin

Question 6

Parts of the nucleus include

Answer 6

• Double nuclear membrane
• Nucleoplasm
• Chromatin/DNA and proteins
• Nucleolus

Question 7

Phase of a cells cycle when the chromatin condenses into distinct chromasomes

Answer 7

Prophase of Mitosis and Meiosis

Question 8

How do you make a karyotype & what do we use it for?

Answer 8

• Cut out images of a cells chromosomes
• Arranged in pairs and numbered in order of size
• Shows chromosomal content of cells
• Can be used to diagnose chromosome level genetic disorders

Question 9

Number of chromosomes in humans

Answer 9

46 chromosomes (23 pairs)

Question 10

Sex chromosomes for a female and a male

Answer 10

• XX = females
• XY = males

Question 11

A gene is?

Answer 11

• A specific portion of DNA
• with a specific sequence
• that determines a particular characteristic of an organism.

Question 12

What exactly do genes code for?

Answer 12

Protein molecules

Question 13

DNA not containing genes

Answer 13

non-coding DNA

Question 14

Extra-nuclear DNA often referred to as mtDNA and cpDNA

Answer 14

mitochondrial DNA and chloroplast DNA

Question 15

Reason for adding salt in a DNA extraction

Answer 15

To condense DNA and proteins after cells have burst

Question 16

Reason for adding detergent in a DNA extraction

Answer 16

To remove membrane lipids

Question 17

Reason for adding protease (e.g. meat tenderiser) in a DNA extraction

Answer 17

To remove proteins from membranes and chromatin

Question 18

Reason for adding ice cold alcohol in a DNA extraction

Answer 18

To purify the DNA as DNA forms a solid precipitate in the alcohol

Question 19

Initially credited with identifying the double helix structure of DNA

Answer 19

• James Watson
• Francis Crick
• (in 1953)

Question 20

Performed the X-ray diffraction and photographed it to help discover the structure of DNA

Answer 20

• Rosalind Franklin
• Maurice Wilkins

Question 21

Repeating units making up DNA are called…

Answer 21

Nucleotides

Question 22

Composition of one nucleotide

Answer 22

• Phosphate
• Deoxyribose
• Nitrogenous base

Question 23

The five different nitrogenous bases

Answer 23

• A-Adenine
• T-Thymine
• C-Cytosine
• G-Guanine
• U-Uracil

Question 24

Purine bases

Answer 24

• Adenine
• Guanine

Question 25

Pyrimidine bases

Answer 25

• Thymine
• Cytosine

Question 26

Nitrogenous base pairing (complementary bases)

Answer 26

• A-T (or A-U in RNA)
• C-G

Question 27

Type of bond between complementary bases

Answer 27

Hydrogen bonds

Question 28

What are polymers?

Answer 28

Compounds made with repeating units (e.g. DNA)

Question 29

The method Watson and Crick employed to discover the structure of DNA

Answer 29

Built a model using already known facts about DNA’s composition and structure

Question 30

The role of DNA

Answer 30

• Carry all the genetic code for an organism
• DNA code is needed for protein synthesis
• Replication provides genetic code for both daughter cells in cell division
• Passing hereditary information from parents to offspring

Question 31

Phases of the cell cycle

Answer 31

• Interphase, made up of:
• First gap phase (G1) - growth in physical size
• Synthesis phase (S) - DNA replication
• Second gap phase (G2) - checking the cell is ready to divide, and
• Mitosis

Question 32

Phase of cell cycle when DNA replication takes place

Answer 32

Interphase - Synthesis phase (S)

Question 33

Errors in DNA code copying during DNA replication that become permanent changes

Answer 33

Mutations

Question 34

Sequence of steps in DNA replication

Answer 34

• DNA unwinds to form a ladder
• Enzymes unwind and unzip DNA, breaking hydrogen bonds
• Template exposed
• Free floating nucleotides in nucleoplasm
• Enzymes control joining of free nucleotides to existing template
• Forming complimentary strands
• Two DNA strands reform

Question 35

Identifying someone using their DNA is called

Answer 35

DNA profiling

Question 36

Main steps in the process of electrophoresis

Answer 36

• DNA loaded into a gel
• Electric current makes DNA migrate towards positive electrode
• Smaller fragments of DNA move faster
• A banding pattern is photographed under ultraviolet light

Question 37

Process of DNA profiling

Answer 37

• DNA from cells is isolated
• Enzymes cut DNA at very specific sites into different lengths (different for each individual)
• DNA fragments are amplified (copied) by PCR
• Electrophoresis is used to identify the DNA profile
• Banding patterns are compared to known DNA samples

Question 38

Arguments for use of DNA profiling

Answer 38

• Solve crimes
• Determine paternity
• Find missing persons
• Identify people/ remains

Question 39

Arguments against use of DNA profiling

Answer 39

• Invasion of privacy for victim and suspect
• Possibility of tampering evidence
• Misuse of technology

Question 40

Give the complementary DNA sequence for: ACTTCTA

Answer 40

TGAAGAT