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Biology: Biological molecules 1&2 > 2.1 Structure of DNA and RNA > Flashcards

2.1 Structure of DNA and RNA Flashcards

1
Q

What does RNA stand for

How many strands does it have

A

Ribonucleic acid

One strand

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2
Q

What does DNA stand for

A

deoxyribonucleic acid

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3
Q

What is DNA made up of and what is the structure of DNA called

A

Its double helix structure

Nucleotides that have 3 basic components

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4
Q

What is the nucleotide structure

A

. A pentose sugar (so called because it has 5 carbon atoms)

. A phosphate group

. A nitrogen containing organic base (ATCG)

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5
Q

What are the names of the bases

A
T
C
G

A

Adenine

Thymine

Cytosine

Guanine

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6
Q

What base is In RNA that isn’t in DNA

A

Uracil (U)

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7
Q

What type of reaction occurs between a pentose sugar, phosphate group, and organic base

A

Condensation reactions to form a single nucleotide
(mononucleotide)

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8
Q

How are mononucleotides joined and what’s the new name

What’s the bond called

A

Condensation reactions also between the deoxyribose sugar of one mononucleotide, and phosphate group of another

Dinucleotide

A phosphodiester bond is formed

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9
Q

What is a polynucleotide

A

Multiple mononuclotides joined together forming a long chain

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10
Q

What is the shape of the symbol for…

Phosphate

Pentose sugar

A

. Circle

. Pentagon

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11
Q

What base does uracil replace in RNA from DNA

A

Thymine

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12
Q

Describe the structure of ribonucleic acid

A

. Ribonucleic acid is a polymer made up of nucleotides

. Single, short chain where the pentose sugar is ALWAYS ribose

. Bases are always Adenine, Cytosine, Guanine, and Uracil
so they have no thymine

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13
Q

What are the 3 types of RNA

MRNA
Ribosomal RNA
Transfer RNA

A

. Messenger RNA: Transfers genetic info from nucleus to ribosomes

. Ribosomal RNA: Ribosomes are made from this type of RNA

. Transfer RNA: Involved in protein synthesis

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14
Q

Who worked out the structure of DNA and when

A

1953

James Watson and Francis Crick worked out the structure

Rosalind Franklin also found X ray diffraction patterns of DNA

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15
Q

What is the pentose sugar in DNA

What are the bases

A

Deoxyribose

Adrenine
Thymine
Cytosine
Guanine

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16
Q

Structure of DNA

A

Made up of two strands of nucleotides (polynucleotides).

Each strand is extremely long

Strands are joined together by hydrogen bonds formed between certain bases

17
Q

What does Adenine pair to

What does Guanine pair to

A

Thymine

Cytosine

18
Q

What is complimentary base pairing

A

. The bases attach to a specific one with hydrogen bonds, that hold the two strands together.

19
Q

How do the quantities of bases vary in DNA

A

The quantities of A and T in DNA are always the same, and so are the quantities of C and G

However, the ratio of AT to CG varies between species

20
Q

What is the name of the structure of DNA

Explain it

A

Double helix

Ladder like arrangement of two polynucleotide chains being twisted

Uprights of phosphate and deoxyribose wind around each other to form double helix

It forms the backbone of the DNA molecule

21
Q

What ways do the uprights run in DNA

A

They go different directions ( Antiparallel)

22
Q

How is DNA a stable molecule

A

. Phosphodiester backbone protects the more chemically reactive organic bases inside the double helix

. hydrogen bonds link the organic base pairs forming bridges between the phosphodiester uprights.
As there are three hydrogen bonds between C and G, the higher the proportion of these pairings, the more stable the DNA molecule

There are other interactive forces between base pairings, holding molecule together

23
Q

How many hydrogen bonds are there between cytosine and guanine

What about between adenine and thymine

What do these bonds do

A

3 between c and g

2 between a and t

They hold the two chains together forming bridges.

24
Q

What is the function of DNA

A

. To contain Hereditary material responsible for passing genetic info from cell to cell and generation to generation

25
Q

There are around 3.2 billion base pairs in the DNA of a typical mammal cell

What does this mean

A

There is an almost infinity variety of sequences of bases along the length of a DNA molecule

26
Q

Why is DNA being stable very important for its function

A

. It’s a very stable structure which passes down generations without significant change.

Most mutations are repaired, so persistent mutations are rare

27
Q

Why is it good that DNA has only hydrogen bonds joining the two strands together

A

Its two strands are joined only by hydrogen bonds between the nitrogenous based which allow them to separate during DNA replication and protein synthesis

28
Q

How is the DNA molecule adapted to carry out it’s function:

Its large

A

Its an extremely large molecule so carries an immense amount of genetic info

29
Q

How is the DNA molecule adapted to carry out it’s function:

Has base pairs within helical cylinder of the deoxyribose phosphate backbone

A

By having base pairs within the helical cylinder of deoxyribose phosphate backbone, the genetic info is to some extent protected from being corrupted by outside chemical and physical forces

30
Q

How do base pairings help DNA transfer information

A

Base pairings lead to DNA being able to replicate and to transfer information as MRNA

31
Q

How are carbon atoms in pentose molecules numbered

A

. Labelled from 1 to 5

3 prime carbon has hydroxyl group

5 prime carbon has the attached phosphate group

They are labelled starting from 1, from the clockwise direction from the O in it.

32
Q

What ways do the strands run in DNA

A

. One strand runs in 5’ to 3’ direction, whilst the other runs in the opposite 3’ to 5’ direction.

The two strands are said to be antiparallel

33
Q

Why can nucleic acids only be synthesised in Vivo

A

This is the 5’ to 3’ direction, because the enzyme DNA polymerase that assembles nucleotides into a DNA molecule can only attach nucleotides to the hydroxyl group on 3’ carbon molecule.

Biology: Biological molecules 1&2 (13 decks)

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