Unit 11 part 1

Question 1

The Flow of Genetic Material

Answer 1

• DNA is inherited by an organism and due to the synthesis of proteins, this leads to expression of specific traits
• The information content of genes is in the specific sequences of nucleotides
• Proteins are the links between genotype and phenotype

Question 2

gene expression

Answer 2

the process by which DNA directs protein syntehsis
- includes transcription and translation

Question 3

RNA is the bridge between

Answer 3

genes and the proteins for which they code

Question 4

Transcription

Answer 4

synthesis of RNA using information in DNA
* Transcription produces messenger RNA (mRNA)

Question 5

Translation

Answer 5

synthesis of a polypeptide, using information in the mRNA
* Ribosomes are the sites of translation

Question 6

• In prokaryotes: (gene expression)

Answer 6

translation of mRNA can begin before transcription has finished

Question 7

in eukaryotic cell (gene expression)

Answer 7

nuclear envelope separates trnascription from translation

Question 8

Eukaryotic RNA transcripts are modified through

Answer 8

rna processing to yield the finished mRNA
- a primary transcript is the initial RNA transcript from any gene prior to processing

Question 9

central dogma

Answer 9

the concept that cells are government by a cellular chain of command
DNA -> RNA -> Protein

Question 10

Flow of information from gene to protein:

Answer 10

• triplet code

Question 11

triplet code

Answer 11

non overlapping, three nucleotide words

Question 12

words of a gene

Answer 12

• transcribed into complementary non overlapping, three nucleotide words of mRNA
• WORDS IN MRNA ARE TRANSLATED INTO AMINO ACIDS, FORMING A POLYPEPTIDE

Question 13

template strand:

Answer 13

• Provides a template for the sequence of complementary nucleotides in an mRNA transcript

Question 14

• Non template strand:

Answer 14

• Nucleotides of this strand are identical to the codons, except U in RNA in place of T in the DNA

Question 15

During translation, the mRNA triplets,

Answer 15

called codons, are read in the 5′ → 3′ direction
- each codon specifies the amino acid to be added ina. growing polypeptide
- from gene (DNA sequence) to protein (polypeptide sequence)

Question 16

• Of the 64 triplets

Answer 16

• 61 code for amino acids
• 3 triplets are stop signals to end translation

Question 17

redundant meaning

Answer 17

the genetic code is redundant
- more than one codon may specify a particular amino acid

an amino acid may have more than one code

Question 18

the genetic code is non ambigious

Answer 18

• no codon specifies more than one amino acid

Question 19

Wobble Hypothesis

Answer 19

Flexible pairing at the third base of a codon allows some tRNAs to bind to more than one codon

Question 20

Cracking the Code

Answer 20

• Codons must be read in the correct reading frame to produce the specified polypeptide

Question 21

Universal Genetic Code

Answer 21

• The genetic code is nearly universal:
• Shared by the simplest bacteria and the most complex animals
• Genes can be transcribed and translated after being introduced to a new species

Question 22

Transcription

Answer 22

• Transcription is the first stage of gene expression
• DNA directed RNA synthesis

Question 23

three stages of transcription

Answer 23

• initiation
• elongation
• termination

Question 24

rna synetheis is catalyzed by

Answer 24

polymerase (not DNA polymerase)

Question 24

RNA polymerase:

Answer 24

* Catalyzes RNA synthesis * Opens DNA strands and joins RNA nucleotides together in 5’ – 3’ direction * Does not need any primer * Follows same base-pairing rules as DNA, except that uracil substitutes for thymine * Produces RNA that is complementary to the DNA template strand

Question 25

Promoter

Answer 25

DNA sequence where RNA polymerase attaches * Transcriptional start point * Usually extend several dozen nucleotides upstream of the start point * A TATA box is crucial in forming the initiation complex in eukaryotes

Question 26

transcription unit

Answer 26

the stretch of DNA that is transcribed

Question 27

in bacteria the sequence signalling the end of trsnacription is called

Answer 27

terminator

Question 28

* Transcription factors:

Answer 28

* Mediate the binding of RNA polymerase and the initiation of transcription

Question 29

* Transcription initiation complex:

Answer 29

* The completed assembly of transcription factors and RNA polymerase II bound to a promoter

Question 30

As RNA polymerase moves along DNA,

Answer 30

it untwists the double helix, 10-20 bases at a time * Transcription progresses at a rate of 40 nucleotides per second in eukaryotes

Question 31

* Nucleotides are added to the

Answer 31

3′ end of the growing RNA molecule

Question 32

termination- bacteria

Answer 32

the polymerase stops transcription at the end of the terminator * mRNA can be translated without further modification

Question 33

in eukaryotes- termination

Answer 33

RNA polymerase transcribes the polyadenylation (polyA) signal sequence; * RNA transcript is released 10–35 nucleotides past this polyadenylation sequence (bunch of AAAA in a row)

Question 34

RNA processing

Answer 34

- enzymes in the eukaryotic nucleus modify pre-mRNA - transcripts are then transported to the cytoplasm - during RNA processing, both ends of the primary transcript are altered

Question 35

Splicing

Answer 35

* Sections of mRNA(introns) are removed, and remaining sections (exons) are spliced together

Question 36

* Each end of a pre-mRNA molecule is modified:

Answer 36

- 5' ends recieve 5' cap - 3' end gets poly-A-tail (AAAA)

Question 37

modifications to the mRNA do what

Answer 37

- help export to cytoplasm - protect mRNA from hydrotic enzymes - help ribosomes attach to 5' end

Question 38

introns

Answer 38

non- coding regions

Question 39

extrons

Answer 39

coding regions, expressed and usually translated into amino acid sequences (importnant ones)