DNA + RNA

Question 1

what does DNA do?

Answer 1

stores genetic information and controls cell activities - it contains the instructions for building all proteins within an organism

Question 2

what form is DNA in eukaryotes?

Answer 2

within the nucleus as linear chromosomes

Question 3

what form is DNA in prokaryotes?

Answer 3

in the cytoplasm in he form of a circular chromosome and many small plasmids

Question 4

what shape is DNA?

Answer 4

a double helix shape (two strands wrapping around each other)

Question 5

what is DNA made of?

Answer 5

nucleotides - they consist of a sugar (deoxyribose), a phosphate and a nitrogenous base

Question 6

what are the four nitrogenous bases?

Answer 6

adenine, cytosine, guanine, thymine - they are represented by the letters A, C, G and T

Question 7

how are the nucleotides joined together?

Answer 7

by covalent bonds between the sugar of one nucleotide and the phosphate group of the next nucleotide - this forms the sugar phosphate backbone

Question 8

what is adenine always paired with?

Answer 8

thymine

Question 9

what is cytosine always paired with?

Answer 9

guanine

Question 10

will the number of A’s and T’s always be the same as the number of C’s and G’s?

Answer 10

yes - however, there may be more CG pairings than AT in an organism

Question 11

what is RNA?

Answer 11

RNA is a type of nucleic acid called ribonucleic acid

Question 12

how is RNA formed?

Answer 12

• the RNA nucleotides are joined to form a single strand
• the nucleotides are joined by a covalent bond between the sugar of one nucleotide and the phosphate of the next

Question 13

in what ways does RNA differ from DNA?

Answer 13

1. RNA is single stranded while DNA is double stranded
2. RNA has sugar called ribose while DNA has a sugar called deoxyribose
3. RNA has the base uracil (U) while DNA has the base thymine (T)

Question 14

what are the two types of RNA?

Answer 14

mRNA and tRNA

Question 15

what is mRNA?

Answer 15

messenger RNA:
- this is formed in the nucleus of the cell, it copies the sequence of bases of a section of DNA in a process called transcription
- mRNA carries the code for building a specific protein from the nucleus to the ribosomes in the cytoplasm

Question 16

what is tRNA?

Answer 16

transfer RNA:
- this is found in the cytoplasm, the tRNA picks up specific amino acids from the cytoplasm and brings them into position on the surface of a ribosome where they can be joined together in specific order t make a specific protein
- this process is called translation

Question 17

what is a gene?

Answer 17

a length of DNA which codes for a protein - this means it provides information on the sequence of amino acids in a protein

Question 18

what do gene proteins control?

Answer 18

chemical reactions, growth, colouration and all inheritable characteristics

Question 19

what is a codon?

Answer 19

the sequence of three bases that code for a specific amino acid e.g. TAG, CCG

Question 20

what does a chromosome being homologous?

Answer 20

genes that control a specific characteristic are situated at the same point on each chromosome

Question 21

what do alleles do?

Answer 21

code for different forms of a protein

Question 22

what is a genome?

Answer 22

one copy of all an organisms DNA - in humans this is all of the DNA that makes up the 23 pairs of chromosomes found in all diploid body cells