biology sem 2 unit 1

Question 1

what does dna stand for?

Answer 1

deoxyribonucleic acid

Question 2

what are the 2 reasons why dna is unique

Answer 2

it contains our genetic code and copies itself exactly

Question 3

what are the building blocks of dna

Answer 3

nucleotides

Question 4

what are the 3 parts of a nucleotide

Answer 4

phosphate, sugar(deoxyribose), and nitrogen base

Question 5

what are the 4 nitrogen bases for dna

Answer 5

adenine, thymine, cytosine, guanine

Question 6

what are the purines and how many rings do they have

Answer 6

adenine and guanine, 2 rings

Question 7

what are the pyrimidines and how many rings do they have

Answer 7

cytosine and thymine, 1 ring

Question 8

when and who discovered the double helix structure of dna

Answer 8

1953; wilkins, watson, franklin, crick

Question 9

what did Erwin Chargaff discover

Answer 9

In any sample of dna thymine and adenine have close to the same percentages, guanine and cytosine then also have close to the same percentages

Question 10

what is the backbone of dna made up of

Answer 10

sugar and phosphate

Question 11

what holds the dna molecule together

Answer 11

hydrogen bonds

Question 12

which are the nitrogen bases always connected to, the sugar or the phosphate

Answer 12

sugar

Question 13

name the complementary strands of dna

Answer 13

adenine-thymine, cytosine-guanine

Question 14

what enzyme unzips the 2 strands of dna in dna replication

Answer 14

dna helicase

Question 15

what does dna polymerase do

Answer 15

link the compliments of the old dna strand together

Question 16

what is mRNA

Answer 16

found in the nucleus, then moves thru nuclear pores to cytoplasm, single, uncoiled chain; carries genetic info of dna in the nucleus to the cytoplasm

Question 17

tRNA

Answer 17

found in cytoplasm. Bonds to a specific amino acid and carries that amino acid to the ribosomes

Question 18

rRNA

Answer 18

found in the ribosome(in cytoplasm), rRNA functions in the ribosomes as a metabolic molecule that aids in protein synthesis. (most common type, least understoood)

Question 19

what are the 4 differences between dna and rna

Answer 19

Dna- 2 strands, deoxyribose(5-carbon sugar name), has thymine, stays in nucleus. Rna- 1 strand, ribose(5 carbon sugar name), uracil, can leave the nucleus

Question 20

what is transcription and where does it occur

Answer 20

Rna molecules are produced by copying part of the nucleotide sequence of dna into a complementary sequence in rna; occurs in nucleus

Question 21

step 1 of transcription

Answer 21

rna polymerase binds to a specific region of a dna molecule called the promoter site

Question 22

step 2 of transcription

Answer 22

Separation of complementary strands of dna occurs

Question 23

step 3 of transcription

Answer 23

Rna polymerase then uses one strand of dna as a template from which nucleotides are assembled into a strand rna

Question 24

step 4 of transcription

Answer 24

Rna polymerase reaches the termination site and the newly made rna is released

Question 25

step 5 of transcription

Answer 25

The new rna strand moves from the nucleus to the cytoplasm though the nuclear pores. In the cytoplasm it will be read by a ribosome to make a protein

Question 26

what enzyme is responsible for transcription

Answer 26

rna polymerase

Question 27

how does mRNA move from the nucleus to the cytoplasm of a cell

Answer 27

it moves through nuclear pores

Question 28

a series of 3 mRNA nitrogen bases that contain the info needed to make proteins are called what

Answer 28

codons

Question 29

what is the universal start codon and what amino acid does it code for

Answer 29

AUG, methionine

Question 30

what are the 3 stop codons

Answer 30

UGA, UAG, UAA

Question 31

what is translation and where does it occur in the cell

Answer 31

The sequence of nitrogen bases in the newly made mRNA strand is translated into a chain of amino acids in the cytoplasm at the ribosome; occurs in the cytoplasm

Question 32

step 1 of translation

Answer 32

mRNA made a copy of dna and then the mRNA exits the nucleus thru nuclear pores and enters the cytoplasm

Question 33

step 2 of translation

Answer 33

tRNA is now activated to pick up a specific amino acid in the cytoplasm. tRNA transports the amino acid to the ribosome

Question 34

step 3 of translation

Answer 34

When a tRNA anticodon binds to the mRNA codon, the amino acid it carries detaches from the tRNA and attaches to the end of a growing protein chain via peptide bonds

Question 35

step 4 of translation

Answer 35

Once the a.a. has joined the protein chain, the tRNA detached from the mRNA strand

Question 36

what does the word mutation mean

Answer 36

to change

Question 37

mutations that produce changes in a single gene are called

Answer 37

gene mutations

Question 38

mutations that produce changes in a whole chromosome are known as

Answer 38

chromosomal mutations

Question 39

in what ways do most mutations affect organisms

Answer 39

most mutations have little to no affects

Question 40

what are 3 examples of gene (point) mutations

Answer 40

substitution, insertion, and deletion

Question 41

what does it mean that insertions and deletions usually result in a frameshift

Answer 41

A nitrogen base is added or taken away from the mrna strand which shifts the reading of the strand since the codons are read in 3s. So there would be a new grouping of 3s which shifts everything.

Question 42

what are the 4 types of chromosomal mutations

Answer 42

translocation, inversion, deletion, and duplication

Question 43

explain translocation

Answer 43

affects 2 different chromosomes, worst one, when one part of a chromosome breaks off and joins another

Question 44

explain duplication

Answer 44

affects 1 chromosome, produces an extra copy of all or part of a chromosome, causes the original and duplication to cancel each other out

Question 45

explain deletion

Answer 45

affects 1 chromosome, loss of all or part of a chromosome

Question 46

explain inversion

Answer 46

affects 1 chromosome, switches parts of the chromosome right next to each other which changes the order of the original chromosome

Question 47

what are the 3 types of substitutions

Answer 47

missense, nonsense, and silent

Question 48

explain missense

Answer 48

if a substitution changes the amino acid

Question 49

explain silent

Answer 49

if the substitution doesn't change the amino acid

Question 50

explain nonsense

Answer 50

if the substitution changes the amino acid to a stop codon