DNA, RNA and protein synthesis: DNA, genes and chromosomes

Question 1

How is DNA stored in eukaryotic cells

Answer 1

• Bc the DNA is linear and exists as chromosomes
• It is stored in the nucleus, and has to be wound up around proteins called histones because it is so long WHICH supports the DNA
• The DNA is coiled very tightly to make a compact chromosome

Question 2

How is DNA stored in prokaryotic cells

Answer 2

• Prokaryotic cells carry DNA as chromosomes, but bc the DNA is shorter and circular, it isn’t wrapped around histones, so condenses into the cell by supercoiling

Question 3

How does DNA in eukaryotic cells different from in prokaryotic cells

Answer 3

• DNA in eukaryotic cells are found in the nucleus AND are long, linear and associated with histone proteins to form chromosomes

WHEREAS

• DNA in prokaryotic cells are short, circular and are NOT associated with histone proteins, so they condense by supercoiling

Question 4

Describe the DNA within the mitochondria and chloroplast

Answer 4

• They are prokaryotic-like BC they are shorter, circular and isn’t wrapped around histones

Question 5

What organelles within eukaryotes contain their own prokaryotic-like DNA

Answer 5

• Mitochondrion
• Chloroplasts

Question 6

What is a gene

Answer 6

A gene is a sequence of DNA bases that codes for a polypeptide or functional RNA

Question 7

What determines the order of amino acids in a polypeptide

Answer 7

The order of the bases

Question 8

What forms the primary structure in proteins

Answer 8

The sequencing of amino acids

Question 9

How is each amino acid coded for

Answer 9

By a sequence of three bases in a gene called a triplet/codon

Question 10

What do genes that don’t code foe a polypeptide code for instead

Answer 10

Functional RNA such as tRNA and rRNA

Question 11

What is functional RNA

Answer 11

• They are RNA molecules other than mRNA which perform special tasks during protein synthesis
• tRNA and rRNA

Question 12

What is a cell’s genome

Answer 12

The complete set of genes in a cell

Question 13

What is a cell’s proteome

Answer 13

The full range of proteins that the cell is able to produce

Question 14

What are introns

Answer 14

Sections of a gene that codes for polypeptides, that doesn’t actually code for amino acids

Question 15

What are exons

Answer 15

The sections of a gene that actually code for amino acids (separated by one or more introns)

Question 16

When are introns removed, why

Answer 16

They are removed during protein synthesis so it doesn’t affect the amino acid order

Question 17

Which type of DNA does not have introns

Answer 17

Prokaryotic DNA does not have introns

Question 18

What is an allele

Answer 18

Prokaryotic DNA does not have introns

Question 19

What us a locus

Answer 19

The physical site of a specific gene on a chromosome

Question 20

Where are introns found

Answer 20

They are found between exons within genes

Question 20

What makes two genes alleles

Answer 20

• When the order of bases in each gene is slightly different
• Causing the production of slightly different versions of the same polypeptide

Question 21

What is a homologous pair

Answer 21

They are pairs of matching chromosomes

Question 22

Describe the features of a homologous pair

Answer 22

• They are the same size and the same genes - but could have different alleles
• Alleles coding for the same characteristic will be found at the same fixed position (locus) on each chromosome

Question 23

How many chromosomes do humans have

Answer 23

23 pairs of chromosomes (46 chromosomes total)