18.3

Question 1

What is a permanent change in the genetic material of an organism?

Answer 1

Mutation

Question 2

What are somatic cell mutations?

Answer 2

Mutations that occur in body cells

Question 3

What are germ cell mutations?

Answer 3

Mutations that occur in reproductive cells

Question 4

What are point mutations?

Answer 4

Permanent changes that affects just one or a few nucleotides - small change

Question 5

What is a silent mutation?

Answer 5

Mutation that has no affect on the cells metabolism or the protein that is produced

Question 6

What is a mis sense mutation?

Answer 6

When a substitution leads to a slightly altered but still functional polypeptide

Question 7

What is a result of a mis sense mutation?

Answer 7

Sickle cell anemia - change of a single amino acid in on of the polypeptides that make of hemoglobin

Question 8

What are non sense mutations?

Answer 8

Mutations that render the gene unable to code for a functional polypeptide - start signal is deleted or there is a premature stop codon

Question 9

How many stop codons are there, and what are they?

Answer 9

There are three stop codons
* UAA
*UGA
*UAG

Question 10

How many start codons are there, and what are they?

Answer 10

One start codon
* AUG

Question 11

What is a frame shift mutation?

Answer 11

Causes the entire reading frame of a gene to be altered

Question 12

Do nucleotide substitutions affect neighboring code sequences?

Answer 12

NO

Question 13

How many genes do point mutations affect?

Answer 13

Only one gene

Question 14

What happens when there are mutations that rearrange the genetic material.

Answer 14

Several genes can be affected, including genes located on different chromosomes

Question 15

What are two examples of chromosomal mutations?

Answer 15

• Crossing over - recombines genetic material on different chromosomes
• DNA replication - the loss or duplication of a portion of chromosome - change in the structure of DNA sequences

Question 16

What is spontaneous mutations, and what is a source?

Answer 16

Mutations that are caused by molecular interactions that take place naturally in the cell
* Incorrect base pairing by DNA polymerase during the process of DNA replication

Question 17

What are induced mutations?

Answer 17

Mutations that are caused by agents that are outside the cell

Question 18

What is a mutagen?

Answer 18

A substance that increases the rate of a mutation in an organism

Question 19

What are two types of mutagens?

Answer 19

A physical mutagen and a chemical mutagen

Question 20

What do physical mutagens do, and what are examples of physical mutagens?

Answer 20

They cause physical changes in the structure of DNA(breaks nucleotide sequence)

X ray, UV radiation, gamma rays

Question 21

What do X rays do?

Answer 21

They are high form of radiation that tear through DNA molecules
* causing random changes from point mutations to the loss of large proportions of chromomes

Question 22

What does UV radiation do?

Answer 22

It causes a chemical reaction between adjacent pyrimindes Thymine and Cytosine
* Distortion of the DNA molecule that interferes with replication

Question 23

What can be caused from UV radiation?

Answer 23

Cancer - melanoma

Question 24

What are chemical mutagens?

Answer 24

Mutagens that enter the nucleus of a cell and induce mutations by reacting chemically with DNA

Question 25

How can a chemical mutagen insert itself in a cell?

Answer 25

* May insert in a manner that causes point mutations or frameshift mutations * May have a structure that is similar to to the ordinary nucleotides but with different base pairing properties

Question 26

What are chemical mutagens that are associated with one or more forms of cancer?

Answer 26

Carcinogenic mutagens

Question 27

What is the definition of cancer in molecular terms?

Answer 27

The result of somatic cell mutations that disrupt the expression of genes in the regulation of the cell cycle

Question 28

Does a single mutation have an effect on a living cell?

Answer 28

No

Question 29

What is responsible for some of the tremendous variation that we see?

Answer 29

The accumulation of mutations over time

Question 30

What are the two factors for mutations?

Answer 30

They can be inherited * or the result of exposure to mutagens in the environment

Question 31

Which things do not share a similar genetic code?

Answer 31

* Mitochondria and chloroplasts * They have their own DNA, and their genome is replicated, transcribed, and translated independently from the DNA in the nucleus of the cell

Question 32

What is the endosymbiont theory?

Answer 32

Eukaryotic cells arose through a process in which one specifics of prokaryote engulfed another

Question 33

What is mitochondrial DNA used for?

Answer 33

To gather information about the history of an individual species * If two people have identical mtDNA sequences - they most likely share a relatively maternal ancestor

Question 34

What is examining genetic variations among deferent species?

Answer 34

Study of biological diversity

Question 35

What is a crucial tool in the study of biological diversity and evolution?

Answer 35

Non coding stretches of DNA

Question 36

What do non coding stretches of DNA do?

Answer 36

They have a higher mutation rate than the DNA within genes * The higher the mutation rate - the more genetic variation there is between the same species

Question 37

What is genetic engineering?

Answer 37

Working in a laboratory, and manipulating genetic material to alter genes and blend plant, animal and bacterial DNA

Question 38

What is a recombinant DNA?

Answer 38

A molecule of DNA that includes genetic material from different sources

Question 39

What do prokaryotic organism use to defend themselves against infection by foreign bacteria?

Answer 39

They use restriction enzymes

Question 40

What do restriction enzymes do?

Answer 40

catalyze the cleave of DNA at a specific nucleotide sequence

Question 41

What are restriction endonucleases?

Answer 41

Restriction enzymes that cuts the interior of a DNA molecule rather than at the end

Question 42

What is the target sequence?

Answer 42

The nucleotide sequence that restriction enzymes targets

Question 43

What is the restriction site?

Answer 43

The point that the DNA strand is cut

Question 44

What two characteristics of DNA make it useful to genetic engineers?

Answer 44

* Specificity - Cuts made by RE are specific and predictable - The DNA is cut the same way each time into identical small DNA fragments * Staggered cuts - RE leave unpaired nucleotides on a single strand at each end of the restriction fragment (sticky ends) - Can form base pairs with one another with a restriction fragment by the action of the same restriction endonuclease on a different strand

Question 45

What splices the sticky pairs together that forms base pairs?

Answer 45

DNA ligase

Question 46

What is gel electrophoresis?

Answer 46

* The tool used to sort and analyze DNA fragment

Question 47

How does gel electrophoresis separate DNA fragments ?

Answer 47

They separate them according to mass and charge

Question 48

What is the process of gel electrophoresis?

Answer 48

1. Solution that contains DNA fragments is applied at one end of a gel 2. An electric current is passed through the gel - causes one end of the gel to develop a positive charge and the other negative charge 3. Because DNA is negative it will move towards the positive side - smaller fragments move down 4. After a period of time - fragments separate into a pattern of bands (DNA fragments)