Chapter 3.8 To The End (DNA PROTEIN SYNTHESIS ETC))

Question 1

What makes a nucleic acid a nucleic acid

Answer 1

If it contains the elements carbon, hydrogen and oxygen , nitrogen and phosphorus too!

Question 2

What do all nucleotides no matter what have

Answer 2

• A pentose monosaccharide (sugar)
• a phosphate group
• a nitrogenous base , containing one or two carbon rings with nitrogen

Question 3

How do nucleotides join?
Where are these
What is it called

Answer 3

condensation reactions

• between the phosphate group of one nucleotide on the 5th carbon of the sugar
• and the hydroxyl group OH on the third carbon

= phosphodiester bonds , covalent and STRONG

Question 4

What is the long chain of sugar and phosphate formed by phosphodiester rebounds called

How can break

Answer 4

This is the sugar phosphate backbone

Broken by hydrolysis reactions that require adding a water

Question 5

What makes the end 3’ or 5’

Other strand?

Answer 5

• connecting nucleotides to each other, the first one will be the 5’ end as this is left (it’s the phosphate group attached to fifth carbon)
• the end will be 3’ as it is OH group left behind.
• This will be reversed on other side as they are ANTIPARALLEL

Question 6

What specific for DNA structure?

Answer 6

• all pentose monosaccharide sugar = deoxyribose
• all have same phosphate group
• nitrogenous bases vary = Adenine thymine cytosine and guanine

Question 7

Ribose vs deoxyribose ?

Answer 7

Both have the OH on carbon 3, fine, that lets the phosphodiester to happen

-Deoxyribose is a sugar WITHOUT oxygen on carbon 2, ribose does!

Question 8

Which are pyrdimines and which are purines

Answer 8

Pyramidine = has a Y= so has to be cytosine and thymine

Thus Purine = what’s left = Adenine and guanine

Question 9

What separates a purine from pyrimidine

Answer 9

Purine are bigger, have DOUBLE RING carbon structure

Pure = big maybe?

Pyrimidine have single ring

Question 10

Why are AT and CG complementary to each other ?

How many bonds

Answer 10

A purine will bind with pyrimidine so AT and CG,
Complimentary be amuse they bind to form specific amount of hydrogen bonds, here

AT= 2
CG =3

Question 11

How is the arrangement if nucleotide in DNA THEN

What does does being antiparallel mean

Answer 11

• First a Strand of a polynucleotide is formed through phosphodiester bonds
  -Two strands of POLYNUCLEOTIDES held together by hydrogen bonds between nitrogen bases
  = this gives a DOUBLE HELIX
• The only way they can be arranged is if they run in oppsoite directions = ANTIPARALLEL

Question 12

Why is the base pairing properties important

Answer 12

It allows for DNA to be copied perfectly and be transcribed

Question 13

Describe the Structure of DNA briefly one more time

Answer 13

A double helix of two antiparallel strands of polynucleotides

Question 14

Why does the fact base pairing is complimentary mean in terms of quantity if each base

Answer 14

It means adenine will always bind to thymine and cytosine always to guanine, thus there always will be equal amount of a to t and c and g !

Question 15

What is an mRNA molecule

Answer 15

A short section of DNA that codes for a gene transcribed into a short RNA molecule called mRNA, still a polynucleotide

Question 16

Structure of RNA

What’s different from DNA too

Answer 16

Pentose monosaccharide = RIBOSE (oxygen on carbon 2)
- phosphate group the same
- nitrogenous base= Adenine guanaine cytosine
and also URACIL instead of THYMINE

2) can only make ONE CHAIN NOT TWO of polynucleotide strand

Question 17

Is uracil purine or pyrimidine and how many bonds formed with adenine (why complimentary still)

Answer 17

Replacing thymine, it is a pyrimidine , so single carbin ring

Makes two hydrogen bonds with adenine so STILL complimentary

Question 18

How to extract DNA from plant in steps

Why

Answer 18

1) grind sample with mortar and pestle
- grinding will break down the cell walls
2) add dna extraction buffer which = detergent, salt and protease enzymes
- detergent breaks up cell membranes, releasing contents of the cell out
- salt breaks down hydrogen bonds between the DNA and the WATER MOLECULEs in solution
- protease enzymes break down peptide bonds of the HISTONE PROTEINS , allowing DNA to come out
3) filter mixture if needed
4) then add ice cold ethanol
- this allows the DNA to precipate out of the solution
- DNA no longer protected so ethanol can keep it protected
5) as it precipates , extract

Question 19

Explain the DNA extraction process again (why do each step)

How can you improve with temp? Or RNAse

Answer 19

1) grinding allows for cell walls to be broken
2) detergent breaks up the cell membrane by dissolving them and thus disrupting structure of the phospholipids, which breaks them apart (like fats on dishes)
- salt breaks the hydrogen binds formed between dna molecules and the water . This causes the DNA TO CLUMP TOGETHER
- and protease enzymes break down histone proteins the dna is wound around, allowing them to no longer be compact anymore and releases them
3) ice cold ethanol forced dna to predicate whilst keeping protected as the dna is exposed now
4) extract it on a splint at an angel or the dna will get DAMAGED

1) heat it so cell stops working and all enzymes denature
2) you could add RNAse before protease to break down any RNA too

Question 20

Why do cells require energy for + examples

3

Answer 20

Synthesis, transport, movement

Synthesis = large from small 
Transport = pumping molecules or  ions across membranes by active transport 
Movement = protein fibres being contracted

Question 21

What is the structure of an ATP nucleotide

Answer 21

• nitrogenous base which is always ADENINE (aden)
• pentose monosaccharide always ribose (osine)
• three phosphate groups (triphosphate)

Question 22

Why is ATP Known as universal energy currency

Answer 22

This is because it is used for energy transfer in all cells of all living things , they all use ATP

Question 23

Why are chains of ATP not made

What happens and why is this a good thing

Answer 23

Three phosphate groups are negatively charged so close will REPEL each other ,
- this makes it unstable, but useful, as the property of losing a phosphate group can be used

Question 24

How does ATP release energy then overall

Answer 24

• unstable phosphate detaches as a bond between breaks.
• a little amount amount for energy is required for this
• but the energy released after when bonds are made in other reactions means overall MORE ENERGY IS RELEASED .
• thus you can say when bonds are “broken” energy is released here

Question 25

What happens chemically to release energy for ATP

When does this happen

Answer 25

Hydrolysis reaction where water is given forms adenosine diphsiohate and another phosphate group , and energy

This happens when reactions need energy, their reactions are coupled with this hydrolysis reaction

Question 26

Where does this energy come, from? What is the cycle of ATP and what are the reactions

Answer 26

Energy comes from long term energy stores like glucose and fats, however getting energy directly from these are hard , so it is stored in ATP first :

• After respiration, energy is used to undergo a ohosphylation reaction, making ADP ATP in a CONDENSATION REACTION RELEASING WATER
• when energy is needed by a cell, HYDROLYSIS OF ATP TAKES PLACE, WHICH OVERALL RELEASES ENERGY

Question 27

What makes ATP a better currency as energy then other sources off energy
5- 6 ways important

Answer 27

• small and can easily move (move into and out of cells easily )
• UNIVERSAL, you can use it anywhere in body, might be harder if you had different energy sources
• Water soluble - can deliver energy to aqueous environments
• releases less energy and in small amounts- so less energy is lost as waste for heat (gkucose would give too much = waste and too fast = waste), these give it the right amounts cells need!
• easily regenerated by energy from respiration
• GOOD IMMEDIATE ENERGY STORE !

Question 28

Why is it a good immediate energy store

Answer 28

Energy let off is immediate due to instability, rather than others which could take time,

• this because phosphylation and hydrolysis of ATP is happening all the time, energy given is instant
• pair this with other benefits like it doesn’t release too much makes it clear why it is better