DNA, genes, alleles and RNA Flashcards

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1
Q

How is DNA stored in eukaryotic cells?

A

As chromosomes where the polynucleotide chain is wound up around histone proteins to form nucleosome
In the nucleus

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2
Q

Where else in a eukaryotic cell is DNA found?

A

In mitochondria
In chloroplasts (if a plant cell)

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3
Q

Features of eukaryotic nucleic DNA

A

Very long
Linear
Associated with proteins
DNA is only visible when it has condensed in mitosis otherwise exists as chromatin

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4
Q

Features of DNA in chloroplasts/ mitochondria

A

Shorter molecule
Circular: no free ends
Not bound to histone proteins

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5
Q

How is DNA stored in prokaryotic cells?

A

Found freely in the cytoplasm as long loops of DNA (additional plasmid loops)

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6
Q

Features of DNA in prokaryotic cells

A

Shorter molecule
Circular: no free ends
Not bound to histone proteins
+ additional circular loops of plasmids

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7
Q

What is a gene?

A

A base sequence in a section of DNA that codes for either:
-The amino acid sequence of polypeptide
-A functional RNA eg tRNA or rRNA

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8
Q

How does the gene determine the protein?

A

The sequence of bases in a gene determines the transcribed mRNA (complementary base pairings) which in protein synthesis determines the amino acid sequence (primary structure). This determines tertiary structure based on bonds between R groups

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9
Q

Genome

A

Complete set of genes in a cell inc mitochondrial and chloroplast DNA

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10
Q

Proteome

A

Full range of proteins a cell is able to produce

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11
Q

Cell proteome

A

The set of proteins produced by a specific cell as a result of which genes are turned on and off

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12
Q

Allele

A

An alternative version of the same gene
May possess a different nucleotide base sequence which alters the polypeptide encoded for by a gene

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13
Q

where are genes/ alleles located on a chromosome?

A

On the same gene locus in the chromosome

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14
Q

Homologous pair of chromosomes

A

Chromosomes that possess the same genes at the same gene loci: may or may not have the same alleles (therefore could potentially be a difference in nucleotide base pair)

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15
Q

What is each chromosome in a homologous pair?

A

Maternal (from mother’s female gamete)
Paternal (from father’s male gamete)

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16
Q

What do alleles at a fixed position encode for in a homologous pair?

A

The same characteristic or protein (eg hair colour, eye colour etc) but different variations eg black, brown etc

17
Q

2 Types of RNA

A

Messenger RNA (mRNA)
Transfer RNA (tRNA)

18
Q

Function of messenger RNA

A

Carries genetic code of DNA, to ribosomes in order to synthesise the polypeptide that the base sequence encodes for

19
Q

Structure of mRNA

A

Formed from condensation of RNA nucleotides to form phosphodiester bonds between each
Ribose sugar
Nucleotide bases: Adenine, Uracil, Cytosine, Guanine
Single polynucleotide strand = single helix molecule

20
Q

Function of tRNA

A

Carries the amino acids used to synthesise a polypeptide chain during translation

21
Q

Structure of tRNA

A

Single polynucleotide strand folded into clover shape: hydrogen bonds between complementary base pairs to hold it together
Has amino acid binding site at one end
Has 3 bases at other end known as anticodon