Structures Of Nucleotides Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What are the 3 components of a nucleotide?

A
  • a phosphate group
  • a pentose sugar
  • an organic nitrogenous base
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the two types of organic nitrogenous base?

A
  • Pyrimidine (single ring)
  • Purine (double ring)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Name the pyrimidines

A
  • Thymine
  • Cytosine
  • Uracil
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Name the purines

A
  • Adenine
  • Guanine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where is DNA found?

A

It’s found as chromatin in the nucleus of eukaryotic cells, and small amounts are found in mitochondria and chloroplasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the functions of DNA?

A
  • It carries the genetic code for protein synthesis
  • It replicates in dividing cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does DNA consist of?

A

Two polynucleotide strands twisted into a double helix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What do DNA nucleotides contain?

A

Deoxyribose, a phosphate group and one of 4 organic nitrogenous bases: adenine, thymine, guanine, cytosine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the 2 strands of DNA said to be?

A

Antiparallel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What do the 2 sugar-phosphate backbones do?

A

They protect the genetic information stored within the sequence of bases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How are bases held together in DNA?

A

Hydrogen bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the complementary base pairs in DNA and how many hydrogen bonds do they form?

A

Guanine+Cytosine - 3 hydrogen bonds
Adenine+Thymine - 2 hydrogen bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where is RNA found?

A

Mainly in cytoplasm. Also in nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How many strands does RNA consist of?

A

RNA is a single stranded polynucleotide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What pentose sugar does RNA contain?

A

Ribose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the 4 organic nitrogenous bases found in RNA?

A

Adenine, cytosine, guanine, uracil

17
Q

What is the function of RNA?

A

Involved in protein synthesis

18
Q

What does mRNA do?

A

Carries the genetic code for a specific protein from DNA in the nucleus to ribosomes in the cytoplasm

19
Q

What does tRNA do?

A

This transfers specific amino acids to the ribosome. A single RNA strand forms a cloverleaf shape held together by hydrogen bonds between certain base pairs.

20
Q

What does rRNA do?

A

Together with a protein, forms a ribosome. Ribosomes translate the genetic code and join amino acids together to form polypeptides.

21
Q

What is protein synthesis?

A

A sequence of DNA nucleotides codes for the sequence of amino acids (primary structure) in one polypeptide.

22
Q

What are the 2 stages involved in protein synthesis?

A

Transcription and translation

23
Q

What is transcription and where does it occur?

A

Occurs in the nucleus
DNA is read by enzymes and used to make a single stranded mRNA molecule. This then leaves the nucleus through a nuclear pore and travels to a ribosome in the cytoplasm or rough endoplasmic reticulum.

24
Q

What is translation and where does it occur?

A

Occurs at a ribosome
mRNA attaches to the ribosome and a tRNA molecule brings a specific amino acid. Ribosomal enzymes catalyse the formation of peptide bonds between adjacent amino acids to form the primary structure of a new polypeptide.

25
Q

What does ATP consist of?

A

3 phosphate groups, a ribose sugar and adenine

26
Q

Why is ATP called the ‘universal energy currency’?

A

It provides energy for many metabolic reactions in all living organisms

27
Q

What are the uses of ATP?

A
  • Active transport
  • Muscle contraction
  • Nerve impulse transmission
  • Secretion (packaging molecules into vesicles for exocytosis)
  • Synthesis of complex molecules from smaller simpler molecules eg proteins/Nucleic acids
28
Q

How is ATP formed?

A

The enzyme ATP synthase combines ADP and Pi (inorganic phosphate) in a condensation reaction. This required the input of energy (30.6kJ) in an endergonic reaction. The addition of this phosphate to ADP is called phosphorylation

29
Q

How is ATP hydrolysed?

A

The enzyme ATPase hydrolyses the terminal phosphate bond releasing a small packet of energy (30.6 kJ mol) in an exergonic reaction. This forms ADP and Pi.

30
Q

What are the advantages of using ATP compared with using glucose?

A
  • Glucose - many enzymes needed to release energy. ATP - only one enzyme needed to release energy through breaking one high energy bond
  • Glucose - releases large quantities of energy that may not be needed generating lots of heat. ATP - releases small packets of energy when and where needed
  • Glucose - only releases energy through respiration. ATP - common source of energy for different chemical reactions (universal)
  • Glucose - requires proteins to cross a membrane. ATP - easily transported across membrane.