4A - DNA, RNA And Protein Synthesis Flashcards Preview

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Flashcards in 4A - DNA, RNA And Protein Synthesis Deck (20):
1

Eukaryotic DNA

- Linear DNA - chromosomes
- long and wound up
- wound around proteins called histones
- histones help to support the DNA
- coiled up tightly to make a compact chromosome

Mitochondria and chloroplasts have own dna

2

Prokaryotic DNA

Shorter and circular
- also carry chromosomes
- no histones
- condensed by supercoiling

3

DNA contains genes

Gene= a sequence of DNA bases that codes for a polypeptide or functional RNA
- sequence of amino acids forms the primary structure of a protein
- different polypeptides have a different number and order of amino acids. It’s the order of the bases in a gene that determines the order of amino acids in a polypeptide

4

How is an amino acid coded for

By a sequence of 3 bases called a triplet

5

First stage of protein synthesis

DNA is copied into mRNA

6

Functional RNA

Genes that don’t code for a polypeptide code for functional RNA instead. Which is rna molecules other than mRNA whcih perform special tasks during protein susnthesis

tRNA

rRNA

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Genome

Complete set of genes in the cell

8

Proteome

Full range of proteins that the cell is able to produce

9

Introns

- the section of some genes that do code for polypeptides contain sections that’s DONT code for amino acids

-can be several within a gene

Removed during protein synthesis so they don’t affect the amino acid order

Only in eukaryotes

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Exon

Bit of gene that does code for an amino acid

11

Non coding repeats

Regions of multiple repeats

DNA sequences that repeat over and over

-don’t code for amino acids

CCTTCCTTCCTT

12

Alleles

Genes can exist in more than one form

= different versions of the same polypeptide

- due to order of bases in each allele

13

About homologous chromosomes

23 pairs of chromosomes

Pairs of Matching chromosomes

Both chromosomes are the same size and have the same GENES , although the could have different alleles

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Locus

Fixed position where alleles coding for the same locus on each chromosome in a homologous pair

15

mRNA

- made during transcription
- carries genetic code from DNA to ribosomes, where it’s used to make a protein during translation
- single polynucleotide strand

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Codons in mRNA

3 adjacent bases

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TransferRNA

- involved in translation
- carries the amino acids that are used to make proteins to the ribosomes
- a single polynucleotide strand
-folded in a clover shape ; by hydrogen bonds
- anticodon at one end abs amino acid binding sure at the other end

18

Anticodon in tRNA

Specific sequence of 3 bases at one end

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First stage of protein synthesis

Transcription

20

Transcription

(mRNA copy of a gene is made from DNA)