DNA

Question 1

Typically, DNA evidence is done for these four crimes?

Answer 1

sexual assualts
homicide
robberies
missing/unidentified person

Question 2

DNA stands for..?

Answer 2

Deoxyribonucleic acid

Question 3

WHat is DNA?

Answer 3

the instruction for each of our cells.

Question 4

Where does DNA come from?

Answer 4

Half from sperm, half from egg.

inherited 23 chromosomes man, 23 woman

Question 5

What does DNA do?

Answer 5

determined an individual’s physical feature.

• hair
• eye colour
• skin colour
• height
• shape of facial feature
• blood type, etc.

Question 6

Where in our cell is DNA found?

Answer 6

in the Nucleus, pocket in the middle of the cell.

Question 7

Approximately how many genes do humans have?

Answer 7

40 000

Question 8

DNA looks like a twisted ladder, what is its name?

Answer 8

double helix

Question 9

What are the four chemical units of our DNA?

Which goes with which?

Answer 9

A- adenine
G- guanine
T- thymine
C- cytosine

A-T
C-G

Question 10

What is the genome?

Answer 10

Ensemble of your DNA. The sequence of letters, the ensemble.

Question 11

Small sections of the genome are called…? Those are short ____ to be understood by ____.

Answer 11

genes
messages
cells

Question 12

What is the RNA?

Answer 12

DNA can be recoded to become RNA, to become protein, to heals, growth, etc.

Question 13

What does RNA stand for?

Answer 13

ribonucleic acid

Question 14

All cells in our body has 46 chromosomes except?

Answer 14

1- gametes only have 23

2- red blood cells have zero

Question 15

DNA human sequence is ____% the same, thus we are ___ unique.

Answer 15

99. 9%

0. 1%

Question 16

More than ____ possible combinations arise from just two parents.

Answer 16

8 trillion

Question 17

DNA fingerprinting:

DNA is found in almost every cell of the body, it is extracted from _____ such as bones and teeth.

Answer 17

tissues

Question 18

DNA is found in _____, hair (if ____ ____), ____, ____ (cells from ____ ducts and mouth), ____ blood cells and any item that was ____ or ____ by suspect or victim.

Answer 18

skin
follicular tag
semen
saliva - salivary 
white 
touched 
worn

Question 19

What is a chimera? Explain why it sometimes happen?

Answer 19

Someone who acquired 2 DNAs in the process of embryonic development.
- 2 eggs fertilize and fuse instead of twins.

Question 20

As of a dutch researcher, what % of the population is a chimera?

Answer 20

30%

Question 21

Why and how (2 ways) we preserve DNA?

Answer 21

no degradation of the DNA
1- dried and stored
2- frozen if cant be dried

Question 22

Though we share most of our DNA, areas of it are ______ (meaning they take different forms) and make some parts unique to everyone.

Answer 22

polymorphism

Question 23

What are the 3 types of samples that are necessary when doing DNA fingerprinting?

Answer 23

1- the samples found at the crime scene.
2- reference samples: victim, suspect if any
3- elimination samples: past sexual partners, first responders, everyone who worked at the crime scene or is involved in the case.

Question 24

1- In order to collect DNA, which means separating from the material in which it is trapped, five steps need to be done. Name them.
PS: remember that some steps require you to name the substance that is used.

Answer 24

1- collect the cells
2- break up the cell membrane (to access the nucleus) - use Lysis Buffer
3- digest the protein to release the DNA with protease
4- precipitate DNA with cold alcohol.
5- determining the [ ] of DNA - how much DNA we have

Question 25

2- Cutting/amplifying DNA:

How do we go about cutting DNA?

Answer 25

use restriction enzymes (endonuclease) that act as molecular scissors.
Those cut sequences of the bases they recognize.
separates into several fragments of DNA

Question 26

What is a base in DNA?

Answer 26

A, T, G, C

Question 27

After the DNA has been cut, how do we amplify the DNA?

Answer 27

add polymerase chain reaction (pcr) to increase the quantity of DNA

Question 28

3- In step 3 of analyzing and observing DNA - we must separate the fragments of DNA with ______.

Answer 28

electrophoresis

Question 29

The ___ gel electrophoresis separates DNA fragments by ___ when an ________ is sent through the gel. This causes the DNA to ____.

Answer 29

agarose
size
electric current
migrate (move)

Question 30

Explain in your own words the process of separating the fragments of DNA:

tips:
- substance must be named
- what happens to the DNA fragments

Answer 30

• the DNA fragments are dissolved into a loading buffer (which is a substance that contains dye and density agents).
• The density of the loading buffer is more important than the one of the agarose gel electrophoresis buffer.
• When we load this mixture with electricity - the DNA sample goes to the bottom.
• The DNA fragments are negative thus pulled towards the anode (positive pole) when into an electric field.

Question 31

Why do the smaller fragments of DNA end up at the bottom?

Answer 31

gel acts like a sieve (which means tami or filtre)

Question 32

What are the two dyes in the loading buffer? What color are they?

Answer 32

Bromophenol blue and xylene cyanol

Question 33

Name the 2 techniques used to visualize DNA?

Answer 33

1- southern blot - fragments of DNA are transferred onto a nylon membrane
2- stain DNA gel - pinpoints the location of the fragments because the staining agent attaches to the said fragments.

Question 34

What is CODIS?

Answer 34

Combined DNA index system -

database with DNA fingerprints/body fluids from felons.

Question 35

Name 8 things we can do with DNA Fingerprinting in the real world.

Answer 35

1- Food ident
2- Convict/or not felons
3- ident human/animal remains
4- relatedness between humans 
5- relatedness in ancient times (history purposes)
6- Reconstruct families 
7- ident organism causes diseases
8- paternity testing