DNA and proteinsynthesis.

Question 1

what does DNA stand for?

Answer 1

deoxyribonucleic acid

Question 2

what is DNA made from?

Answer 2

chain of sugar-phosphates and one of four bases

Question 3

what does DNA do?

Answer 3

codes for individual proteins
contain instructions on how to build proteins used in the body

Question 4

where is DNA found?

Answer 4

the cell nucleus

Question 5

what are the complementary base pairs of DNA and how are they held together?

Answer 5

A + T (straight A, straight T)
C + G (curly C, curly G)

held together by hydrogen bonds (2 between A/T, 3 between C/G)

Question 6

what is the ‘back bone’ of DNA made of?

Answer 6

sugar (deoxyribose) and phosphate

Question 7

what is a genome?

Answer 7

an organisms complete set of DNA

Question 8

what structure does DNA have?

Answer 8

double helix

Question 9

what is a protein?

Answer 9

a polymer of units linked by peptide bonds

Question 10

what are proteins made from?

Answer 10

built of 20 amino acids

Question 11

where are proteins made?

Answer 11

ribosomes

Question 12

what to proteins do?

Answer 12

they perform nearly all biological functions: enzymes, antibodies, structural bodies, hormones

Question 13

what is messenger RNA (mRNA)?

Answer 13

intermediary messenger, takes DNA from nucleus to ribosomes in cytoplasm to create proteins

Question 14

what does RNA stand for?

Answer 14

ribosenucleic acid

Question 15

what sugar group makes up RNA?

Answer 15

ribose

Question 16

what does RNA do?

Answer 16

codes for proteins that cell needs

Question 17

what’s the difference between DNA and RNA bases?

Answer 17

in RNA, adenine (A) pairs with uracil (U) instead of thymine (T)

Question 18

what are the two stages of protein synthesis?

Answer 18

transcription
translation

Question 19

why is mRNA created during transcription?

Answer 19

proteins are made in the cell cytoplasm but the code for these is found in DNA
but DNA is too big to move out of the nucleus so a molecule of messenger RNA (mRNA) is created

Question 20

steps of transcription:

Answer 20

1. an enzyme called RNA polymerase attaches to the DNA in front of a gene in a non-coding region
2. the enzyme separates the DNA strands, and moves along one strand (the template strand) adding complementary RNA nucleotides- these are the same bases as DNA except that uracil replaces thymine
3. the nucleotides are linked to form a strand of messenger RNA (mRNA) which leaves the nucleus through nuclear pores where it is met by a ribosome and is ready to undergo TRANSLATION
4. the DNA strands then join back together

Question 21

what is transfer RNA (tRNA)?

Answer 21

a unit which carries specific, individual, amino acids

Question 22

steps of translation:

Answer 22

1. the mRNA strand attaches to a ribosome in the cytoplasm and is read’ 3 bases at a time (a codon)
2. a tRNA molecule with a complementary anticodon lines up and carries a specific amino acid
3. as the ribosome moves along, it joins the amino acids from the tRNA together, forming a polypeptide
4. the polypeptide chain made up
   of amino acids then folds up to form a protein (i.e. an enzyme) with a specific shape. some proteins contain more than one polypeptide chain.

Question 23

what is the purpose of tRNA molecules in translation?

Answer 23

tRNA molecules bring amino acids to the ribosome (every amino acid has it’s own tRNA molecule)
the mRNA provides the code for the correct order of amino acids
each tRNA molecule has an anticodon which matches the base triplets on the mRNA chain - base triple codons