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AQA A-level Biology Year 1 > Chapter 8 > Flashcards

Chapter 8 Flashcards

1
Q

What is the definition of a gene?

A

Is a section of DNA that contains the coded info for making polypeptides + functional RNA

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2
Q

What form is coded information in?

A

In the form of a specific sequence of bases along the DNA molecule

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3
Q

What do genes determine?

A

Determine proteins of an organism
+
Nature and development of all organisms

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4
Q

Where is the gene located?

A

Located at a particular position called locus

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5
Q

The gene is a base sequence that codes for……

A

Amino acid sequence of a polypeptide

or functional RNA (ribosomal RNA + tRNA)

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6
Q

Why must there be a minimum of 3 bases that code for each amino acid?

A
  • Only 20 different AA regularly occur in proteins
  • Each AA must have its own code of bases on DNA
  • Only 4 bases(A,T,G,C)
  • 3 bases produce 64 (4^3) different codes, more than enough to satisfy requirements of 20 amino acids
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7
Q

What is a code that has 3 bases for each AA called?

A

A TRIPLET

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8
Q

What are some feautures of a genetic code

A
  • Few AA coded by only a single triplet (remaining coded between 2+6 triplets)
  • Triplets always read in 1 particular direction along DNA strand
  • Start of DNA sequence codes for a polypeptide always same triplet
  • Code is universal
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9
Q

Why is the genetic code also known as the ‘degenerate code’

A

Because most amino acids are coded for more than 1 triplet

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10
Q

What does it mean if the code is non-overlapping?

A

Each base in sequence is read-only once (e.g 123456 would be read as 123 , 456)

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11
Q

What are introns?

A

…

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12
Q

What are extrons?

A

…

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13
Q

Why is much of DNA in eukaryotes does not code for polypeptides?

A

between genes, there are non-coding sequences made up of multiple repeats of base sequences

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14
Q

Describe the RNA structure?

A
  • Pentose sugar
  • Organic bases (A,T,G,U)
  • Phosphate group
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15
Q

What two types of RNA are important for protein synthesis?

A

mRNA

tRNA

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16
Q

What is the structure of the mRNA?

A

-Long strand arranged in a single helix (Consisting of thousand of mononucleotides)

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17
Q

How is the structure of mRNA suited to its function?

A

it possesses info in form of codons

-The sequence of codons will determine AA sequence of a specific polypeptide that will be made

18
Q

What are codons?

A

A sequence of 3 adjacent (bases) adjacent nucleotides in mRNA that codes for one amino acid.

19
Q

What happens to mRNA when its formed in the nucleus?

A

mRNA leaves the nucleus via pores in nuclear pores + enters the cytoplasm
- Associates with ribosomes + acts as a template for protein synthesis

20
Q

What is the structure of tRNA?

A

Relatively small molecules (made of 80 nucleotides)

  • Single-stranded folded into a clover shape
  • Part of mRNA which amino acid can attach easily
21
Q

What is in the opposite end of tRNA?

A

Anticodons (sequence of 3 other organic bases)

22
Q

Because the genetic code is degenerate there must be…

A

as many tRNA as there are coding triplets
however
each tRNA is specific to each AA + each AA is specific to the anticodon

23
Q

What is an anticodon?

A

A sequence of 3 adjacent molecules on a molecule of tRNA that is complementary to a particular codon on a mRNA

24
Q

What is an Allele?

A

One of a number of alternative forms of a gene

25
Q

What is a Homologous chromosome?

A

Two chromosomes that carry the same genes

26
Q

What is a Gene?

A

Section of DNA on a chromosome coding for one or more polypeptides

27
Q

What is centromere?

A

The single point where 2 chromosomes are joined

28
Q

What is a chromosome?

A

Thread line structure made of protein + DNA by which heridatary info is physically passed

29
Q

What is the haploid number?

30
Q

What is the diploid number?

A

The total number of homologous pair

31
Q

What is meiosis?

A

The number of nuclear division in which number of chromosomes is halved

32
Q

What is chromatid?

A

One of the 2 strands of a chromosome that are joined by a centromere

33
Q

Transferring the coded info (8.3)

34
Q

What is a genome?

A

The complete set of genes in a cell (including those in mitochondria + chromoplasts)

35
Q

What is proteome?

A

Full range of proteins produced by genome. Sometimes is called the complete proteome refers to proteins produced by a given type of cell under a certain set of conditions

36
Q

What happens during protein synthesis?

A

An anticodon pairs with 3 complimentary organic bases that make up a codon on mRNA
tRNA structure I structurally suited to its role of lining up amino acids on mRNA template during photosynthesis

37
Q

What is transcription?

A

process of making pre-mRNA using part of DNA as a template

38
Q

Describe the process of transcription?

39
Q

Describe the splicing on preMRNA

40
Q

Describe the process of transcription

AQA A-level Biology Year 1 (10 decks)

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