Biological Molocules 2 Flashcards Preview

A Level Biology: Topic 1 (Edexcel) > Biological Molocules 2 > Flashcards

Flashcards in Biological Molocules 2 Deck (49):
1

What makes up a nucleotide?

5-carbon pentose sugar
Nitrogen-containing base
Phosphate group

2

What is the pentose sugar in RNA?

Ribose

3

What is the pentose sugar in DNA?

Deoxyribose

4

What is the difference between a purine and a pyramidine?

A purine has two nitrogen-containing rings and pyramiding has one

5

What are the most common purines?

Adenine
Guanine

6

What are the most common pyramidines?

Cytocine
Thymine (DNA)
Uracil (RNA)

7

Do nucleotides carry a positive or negative charge?

Negative

8

What reaction joins the components of a nucleotide?

Condensation reaction

9

What is ATP?

The universal energy supplier in cells

10

How does the structure of ATP help it carry out it's function?

The third phosphate bond in the molocule is broken in hydroysis catalysed by ATPase to produce ADP which makes energy

11

What catalyses the hydrolysis of ATP molocules?

ATPase

12

What is the function of nucleic acids?

They carry the information needed to form new cells when copied onto mRNA. It stores genetic information in chromasomes

13

What are nucleic acids?

Chains of nucleotides linked together by condensation reactions that produce phosphodiester bonds between the sugar on one nucleotide and the phosphate group on the next.

14

What bond is in the sugr-phosphate backbone?

Phosphodiester

15

What is the difference between DNA and RNA?

RNA: Single stranded and can fold into complex shapes held together by hydrogen bonds
DNA: Double helix with the sugar-phosphate backbone on the outside and the bases inside held by hydrogen bonds

16

What bond holds the bases of the two DNA strands together?

Hydrogen

17

How many hydrogen bonds are there between bases C and G?

three

18

How many hydrogen bonds are there between bases A and T?

two

19

Why are the strands called 3 prime and 5 prime?

Depends on which carbon atom in the pentose sugar that the first phosphate group in the chain is attatched to

20

What was the conservative model of replication?

The original double helix stays intact and the new helix is made up of entirely new material

21

What is the semi-conservative model of replication?

The DNA is unzipped with new nucleotides lining up along each strand so each new helix had half of the original material and half of the new material

22

How does DNA replicate?

Semi-conservatively
DNA helicase unzips the strands
Free nucleotides join to the exposed bases to form matching pairs
DNA polymerase links the nucleotides along the template strand
DNA ligase catalyses the formation of phosphodiester bonds

23

What role does DNA helicase play in replication?

It unzips the two strands of DNA along the hydrogen bonds

24

What role does DNA polymerase play in replication?

Catalyses the linking up of nucleotides along the template strand, creating new hydrogen bonds

25

What is the role of DNA ligase in replication?

It catalyses the formation of phosphodiester bonds along the sugar-phosphate backbone

26

How is DNA a triplet code?

A sequance of three bases code for each amino acid which are arranged together in a polypeptide chain

27

What is a codon?

A sequance of three bases in DNA or RNA

28

What does T/U bond with?

A

29

What does C bond with?

G

30

Why is it a good thing that DNA is non-overlapping?

A point mutation will only affect a single amino acid

31

What are the main functions of RNA in protein synthesis?

To carry instructions for a polypeptide from the DNA in the nucleus to the ribosomes where proteins are made
It picks up specific amino acids from the protoplasm and carries them to the surface of the ribosomes
It makes up most of the ribsomes themselves

32

Where is mRNA formed?

The nucleus

33

What is the antisense strand?

mRNA

34

What is the sense strand?

DNA

35

How is mRNA created?

The DNA unravels by RNA-directed DNA polymerase and complimentry bases line up alongside the sense strand. Phosphodiester bonds are catalysed along the backbone of the mRNA by RNA polymerase

36

How is the mRNA able to pass through the nuclear envelope?

It's small enough to pass through the pores

37

What is the purpose of mRNA?

To carry instructions for a polypeptide from the DNA in the nucleus to the ribosomes where proteins are made

38

What is the purpose of tRNA?

It picks up specific amino acids from the protoplasm and carries them to the surface of the ribosomes

39

What is the purpose of rRNA?

It makes up most of the ribsomes themselves

40

Where is tRNA found?

The cytoplasm

41

What is an anticodon?

The sequance of three bases found on tRNA

42

How is a polypeptide created?

The mRNA travels to the ribosome where tRNA with the complimentry anticodon binds. The amino acids on the other end of the tRNA join together as the mRNA travels through the ribosome, peptide bonds forming between them.

43

Where is rRNA found?

It is made in the nucleus but makes up 50% of the ribosomes.

44

What is a mutation?

A permenant change in the DNA of an organism

45

How can the body deal with mutations?

It has specific restriction enzymes to cut out or repair broken strands of DNA

46

What are point mutations?

Only one nucleotide is miscopied during transcription

47

What are some different types of point mutations?

Deletion
Substitution
Insertation

48

What is a chromasomal mutation

Changes of the position of genes in chromasomes

49

What is a whole-chromasome mutation?

An entire chromasome is either lost or gained during meiosis