EXAM 1

Question 1

Define Mitosis.

Answer 1

A cell division type in which the two cells produced are identical to the parent cell. Used for growth and repair of somatic cells .

Question 2

Define Meiosis.

Answer 2

A type of cell division which results in gametes. The number of chromosomes in the original parent cell is reduced to half (becoming haploid)

Question 3

What are the stages of mitosis and what occurs at each stage?

Answer 3

Pink Mugs Are The Cutest
PROPHASE: Chromosomes condense, Nuclear envelope disappears, spindle fibres form
METAPHASE: Chromosomes line up on the equator
ANAPHASE: Chromosomes pulled to opposite poles
TELOPHASE: Chromosomes de-condense, Nuclear Envelope reappears
CYTOKINESIS: Cell Plate/Cleavage Furrow

Question 4

What is the mitosis graph?

Answer 4

2n - 4n -2n

one cell - two cells

Question 5

What are the stages of meiosis and what occurs at each stage?

Answer 5

MEISOS 1: separates the homologous chromosomes into 2 intermediate cells.

MEIOSIS 2: like a mitotic division but the chromosomal # stays the same as meiosis 1 (halved)

Question 6

What is a nucleotide?

Answer 6

Basic unit of a nucleic acid. Made up of a phosphate, sugar and base.

Question 7

What is RNA?

Answer 7

A single stand of a polynucleotide chain.

Question 8

Difference Between DNA and RNA ?

Answer 8

?

Question 9

Explain the process of DNA Replication

Answer 9

Step 1:

• double stranded molecule “unzipped” into two single strands by DNA helicase creating a replication fork.

Read 5’ to 3’ .
3’ to 5’ - leading strand
5’ to 3’ - lagging

Step 2:

LEADING: DNA polymerase binds to the strand at the site of the primer and begins adding new base pairs complementary to the strand.

LAGGING: DNA polymerase adds pieces of DNA, called Okazaki fragments, to the strand between primers.

Step 3:

DNA ligase joins Okazaki fragments together forming a single unified strand.

Question 10

What is genetic engineering?

Answer 10

• technology of altering genetic material in living cells so they can perform new functions
• rDNA

Question 11

What is rDNA?

Answer 11

• Recombinant DNA.

- cutting sections from one organism and placing them into another eg bacteria plasmid

Question 12

What are restriction enzymes?

Answer 12

• Enzymes that cut DNA at restriction site

- found in bacteria

Question 13

Define ligation.

Answer 13

-when the cut piece of DNA is joined to the bacterial plasmid

Question 14

What is PCR and what is it used for?

Answer 14

• Polymerase chain reaction
• amplification of a single copy or a few copies of a segment of DNA generating thousands to millions of copies of it.
• PURPOSES: gene cloning,diagnosis and monitoring of hereditary diseases; amplification of ancient DNA,DNA profiling (forensic science and parentage testing)

Question 15

What are the steps involved in PCR?

Answer 15

1: Denaturing (95)– when the double-stranded template DNA is heated to separate it into two single strands.
2: Annealing (50-65)– when the temperature is lowered to enable the DNA primers to attach to the template DNA.
3: Extending (72)– when the temperature is raised and the new strand of DNA is made by the Taq polymerase enzyme.

Question 16

What is gel electrophoresis?

Answer 16

A method used to separate large molecules of nucleic acid and proteins on the basis of size and electrical current.

Question 17

What are the steps of gel electrophoresis?

Answer 17

• DNA is cut up using restriction enzymes
• DNA is mixed with loading dyes so it can be seen and sucrose is added to make DNA heavy
• DNA is added to negative end
• electrical current is turned on and the buffer will carry the electrical charge through the gel with the gel acting as a matrix
• smaller fragments will travel further

Question 18

How is rDNA used in environmental conservation?

Answer 18

-control of pests such as rabbits

Question 19

How is DNA profiling used in environmental conservation?

Answer 19

-pathogen identification eg jarrah dieback

Question 20

How is rDNA used in agriculture?

Answer 20

-genetically modified organisms eg golden rice

Question 21

How is DNA profiling used in agriculture?

Answer 21

-genetic markers eg salt tolerance

Question 22

What are sex-linked traits?

Answer 22

• carried on gender determining chromosome
• X carry the allele
• eg colour blindness, haemophilia, muscular dystrophy

Question 23

What is a stratification fossil?

Answer 23

• soil is layed down in strata
• dead organisms can get trapped and stored as fossils
• layers indicate ages and allow fossils to be compared

Question 24

What is embryology ?

Answer 24

• comparing the very early stages of the development of organisms
• difficult to tell the difference between embryos of different species

Question 25

What are homologous structures?

Answer 25

- organs that are similar in structure but may be used for a different function - High degree of similarity supports the idea of a common ancestor

Question 26

What are vestigial organs?

Answer 26

- structures that are reduced in size and may now appear to have no function - presence of organs not required supports the idea of a common ancestor - eg, appendix, wings in emus, erector pili

Question 27

What is DNA hybridisation?

Answer 27

-determines genetic similarities between 2 organisms by measuring the degree of genetic similarity between pools of DNA sequences

Question 28

How does DNA hybridisation work?

Answer 28

- DNA of one organism is labelled then mixed with the unlabelled DNA to be compared against - mixture is incubated to allow DNA strands to dissociate and reanneal forming hybrid double standard DNA - both sets of DNA are heated (86) so hydrogen bonds are broken - single stranded DNA molecules from both species are mixed and allowed to cool - similar strands of DNA from both species will rename all at complimentary base pairs - hybrid DNA is then reheated with temp that DNA becomes single stranded recorded - higher temp = more similar

Question 29

What is a phylogenetic tree used for?

Answer 29

- used to interpret the degree of relationship between 2 organisms - helps map out the evolutionary history

Question 30

What are the steps in natural selection?

Answer 30

1. Variation - occurs due to random assortment of alleles in gametes used for sexual reproduction, crossing over during meiosis, random mating, mutations 2. Overproduction - more of each kind of organism is produced than can reach maturity 3. Survival of the fittest - organisms with characteristics best suited to their environment will survive more readily 4. Selection pressure - something necessary for survival - if a resource is scarce then those who can obtain this resource will survive 5. Gene pool - alleles that are + or silent will remain in gene pool while - alleles will be removed