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Biology🔬🧬 > Neucleotides > Flashcards

Neucleotides Flashcards

1
Q

nucleic acids

A

polymers made up of monomers

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2
Q

Nucleotides

A
  • phosphate group
  • pentose sugar (ribose, deoxyribose)
  • organic base (nitrogenous base)
    Nucleotide are joined together by phosphodiester bonds in condensation
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3
Q

organic bases

A
  • Double ring structures: Purines (adenine, guanine)
  • Single ring structures Pyrimidines (thymine, cytosine, uracil)
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4
Q

Metabolism

A

All chemical reactions in cells

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5
Q

Catabolism

A

Use to break chemical bonds, which breakdowns large molecules

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6
Q

Anobalism

A

Use to build chemical bonds when building larger molecules

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7
Q

ATP as an energy carrier

A

Adenosine Triphosphate - Molecule that makes energy available formed when chemical reactions release energy
Broken down when energy is needed

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8
Q

Structured of ATP

A

Three phosphate groups, ribose, adenine

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9
Q

ATP and when energy is needed

A

When energy is needed in living organisms- ATPase hydrolyses the bond between 2nd and 3rd phosphate groups in ATP leaving 2

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10
Q

ATP hydrolysed

A

into adenosine diphosphate (ADP) and an inorganic phosphate ion, with release of chemical energy
ATP + water —> ADP + Pi
Reaction is reversible

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11
Q

Phosphorylation

A

Addition of Phosphate to ADP

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12
Q

ATP transfers

A

Transfers free energy from energy rich compounds To cellular reactions when needed eg. Glucose
Energy transfer is inefficient and some energies lost as heat
Energy released in respiration, releasing ATP

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13
Q

ATP as a supplier of energy
Hydrolysis

A
  • Hydrolysis of ATP and ADP involves a single reaction, releasing energy immediately. Whereas breakdown of glucose takes longer for energy to be released
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14
Q

ATP as a supplier of energy
One enzyme

A

Only one enzyme needed to release energy from ATP but many for glucose

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15
Q

ATP as a supplier of energy

smlall amounts

A

ATP releases energy in small amounts, when needed
Glucose (large, all at once)

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16
Q

ATP as a supplier of energy

coomon source

A

Provides common source of energy for many different chemical reactions, increasing efficiency and control by the cell

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17
Q

Role of ATP

A

Provides necessary energy for cellular activity

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18
Q

Role of ATP
Metabolic process

A

To build large, complex molecules from smaller, simpler molecules
Eg. DNA synthesis from nucleotides

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19
Q

Role of ATP
Active transport

A

to change shape or carry a proteins in membranes and allow molecules for ions to be moved against the concentration gradient

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20
Q

Role of ATP
Muscle

A

For muscle contraction, cytokinesis

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21
Q

Role of ATP
Nerve transmission

A

Sodium - potassium pumps actively transport sodium potassium ions across an axon membrane

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22
Q

Role of ATP
Secretion

A

the packaging and transport of secretory products into vesicles in cells

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23
Q

structure of DNA

A

composed of 2 polynucleotides strands wound to form double helix
AGTC

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24
Q

Structure of DNA- bases of sugars

A

Bases of two sugars face each other, pointing inwards
Adenine lines opposite with thymine, guanine with cytosine
hydrogen bonds join the bases and form complementary pairs
A complementary to T, Joined by 2 hydrogen bonds
G complementary to C, joined by 3 hydrogen bonds

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25
Q

Hydrogen bonds in the structure of DNA

A

Maintain the shape of the double helix

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26
Q

Two strands in the structure of DNA

A

Two strands run in opposite directions to each other and are antiparallel

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27
Q

role of DNA

A

Provide genetic code to synthesise proteins

28
Q

How is DNA suited for its role

A
  • Very stable molecule, information contents passes from generation to generation without change
  • Very large molecule, carries large amounts of genetic information
  • Two strands able to separate as they are held by hydrogen bonds
  • As base pairs are on the inside of double helix, within the deoxyribose phosphate backbones, the genetic information is protected
29
Q

structure of RNA

A
  • Single stranded polynucleotide
  • Contains pentose sugar ribose
  • adenine guanine cytosine uracil
30
Q

messenger RNA

A
  • Helical, long single stranded molecule
  • synthesised in the nucleus and carries a genetic code from DNA to the ribosomes in the cytoplasm
  • Different mRNA have different lengths of genes from which they are transcribed
31
Q

ribosomal RNA

A
  • Found in the cytoplasm and comprises large, complex molecules
  • Ribosomes are made of rRNA and protein
  • Site of translation of the genetic code into protein
32
Q

terminal RNA

A
  • Small single stranded molecule, folded into Clover leaf shape
  • 3’ End of molecule has base sequence cytosine - cytosine - adenine where specific amino acid the molecule carries is attached
  • Molecules of tRNA transport specific amino acids to ribosomes in protein synthesis
33
Q

Dna replication

A

Copying of DNA in nucleus during interface

34
Q

Conservative replication

A

Where the parental double helix remains intact
Eg. Is conserved and a whole new double helix is made

35
Q

Semi conservative replication

A

Parental double helix separates into two strands each of which acts as a template for synthesis of a new strand

36
Q

Dispersive replication

A

Two new double helices contained fragments from both strands of the parental double helix

37
Q

meselson- stahl experiment

A

cultured bacterium Escherichia coli for several generations with medium containing amino acids made with N15 (heavy)
Bacteria incorporated N15 in nucleotide and eventually DNA contained only N15
Extracted and centrifuged to show low marking.
Bacteria must be washed before next experiments- to be transferred N14 medium to prevent contamination

38
Q

N14 DNA

A

Centrifuged- Showed midpoint density
Rules out conservative replication theory as it would produce a bond showing parental molecule that is entirely heavy
Intermediate D N a containing half heavy half light

39
Q

After 2nd gen

A

N14 settled at the midpoint and high point
Ruled out dispersive because they would be a mixture of lights and heavy in every strand and only one bond would form
Half of DNA is intermedia and half is light

40
Q

After 3rd gen

A

1/4 intermediate
3/4 light

41
Q

Stages of semi conservative replication
1

A

DNA Helicase ‘unwinds and unzippes’ DNA molecule

42
Q

stages of semi Conservative replication
2

A

This exposes the 2 DNA strands which then act as ‘templates’

43
Q

stages of semi Conservative replication
3

A

Free nucleotides collide with their complementary bases and form hydrogen bonds

44
Q

Stages of semi conservative replication
4

A

DNA polymerase forms phosphodiester bonds between new adjacent DNA nucleotides

45
Q

Stages of semi conservative replication
5

A

Two new DNA molecules are formed each composed of one original template strand and one newly synthesised strand

46
Q

the genetic code

A

DNA contains store of genetic information called genes
base sequence directs which amino acids join together
therefore it determines which proteins are made and which reactions can take place in organisms
TRIPLET CODE

47
Q

biochemical experiments show that

A
  • Polynucleotide strand always has three times the number of bases as amino acids chains is coded for
  • If three bases were removed from polynucleotide polypeptide made would have one fewer amino acid
  • If polynucleotide had three extra bases, polypeptide would have one more amino acid
48
Q

coding for amino acids

A

Three bases code for one amino acid
Therefore four different bases, twenty different amino acids
4^3=64 (More than enough)

49
Q

Properties of the genetic code

A
  • 3 bases in code each amino acid, therefore is a triplet code
  • 64 possible codes but only 20 amino acids found in proteins, more than one triplets can encode each amino acid so code is described as ‘degenerate’/ ‘reduction’
  • Code is punctuated: there are 3 triplet codes that don’t code for amino acids. In mRNA ‘stop’ codons and Mark end of a portion to be translated
  • Universal: Some triplet codes for the same amino acids
  • Non overlapping: each base occurs in only 1 triplet
50
Q

Intron

A

Non-coding nucleotide sequence in DNA and pre mRNA- removed from pre mRNA to produce mature mRNA

51
Q

extron

A

Coding region in the nucleotide sequence of DNA and pre mRNA that remains present in final mature mRNA, after intron has been removed

52
Q

In Eukaryotes

A

Initial RNA version of a code is much longer than the final mRNA and it contains sequences of bases that have to be removed

53
Q

Pre messenger RNA

A

RNA is sometimes called pre-mRNA and sequences (introns) are to be removed

54
Q

introns are cut off

A

Cut off of the pre MRNA using endonucleases and the sequence left (Extron’s) which are joined together/ spliced with ligases

55
Q

Protein synthesis: transcription

A

One strand of DNA acts as a template for the production of mRNA, a complementary section of part of DNA sequence- occurs in the nucleus

56
Q

Protein synthesis: translation

A

mRNA acts as a template to which complementary tRNA molecules attach, and the amino acids they carry are linked to former polypeptide - occurs in the ribosomes in the cytoplasm

57
Q

Transcription Process

first

A
  1. DNA helicase ‘unwinds and unzips’ DNA
  2. Free RNA nucleotide randomly collide with their complementary bases on the coding strand
  3. RNA polymerase forms phosphodiester bonds between adjacent RNA nucleotides, synthesising mRNA
  4. It continues to the stop triplet code, then mRNA is released
  5. mRNA diffuses through the nuclear pores into the cytoplasm, happens in a nucleus
58
Q

Translation Process

A
  1. mRNA associates with a ribosome
  2. Ribosome covers the first two codons
  3. A tRNA with a complementary anticodon to the first mRNA codon, H Bonds to it.
  4. 2nd tRNA with a complementary anticodon to the second mRNA codon
  5. Peptide bond forms between the 2 amino acids
  6. First tRNA is released and the ribosome moves along 1 codon.
  7. This continues until ribosome reaches the stop codon
  8. Polypeptide chain is released and so is the mRNA
59
Q

tRNA and amino acid activation

A
  • Once tRNA is released from the ribosome, it is free to collect another amino acid from the amino acid in the cytoplasm
  • Energy from ATP is needed to attach the amino acid to the tRNA
  • Process of attachment is called amino acid activation
60
Q

Genes and polypeptides
Experi

A
  • experiments on fungus neurospora crassa showed that radiation damage to DNA prevented a single enzyme from being made
61
Q

genes and polypeptide
Experiment lead to

A
  • Led to the one - gene - one enzyme hypothesis
  • One - gene - one polypeptide hypothesis ( Proteins contain more than one polypeptide eh. Haemoglobin)
  • Therefore a gene is a sequence of DNA basis that codes for a polypeptide
62
Q

Post-transitional modification ( Modification of a polypeptide)

A

Base sequence of a gene determines the primary structure of a polypeptide
Polypeptides made on ribosomes are transported through the cytoplasm to the golgi body

63
Q

Primary structure of a polypeptide

A

Structure is functional, but usually is folded in secondary, tertiary or quantenary structure in the ER
In the Golgi body it may be chemically modified

64
Q

How polypeptides can be chemically modified

A
  • Carbohydrates: making glycoproteins
  • Lipids: making lipoproteins
  • Phosphate: making phospho-proteins
65
Q
A

Biology🔬🧬 (11 decks)

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