Chapter 3 section B: Protein Synthesis, Degradation, and Secretion

Question 1

A sequence of DNA nucleotides containing the information that specifies the amino acid sequence of a single polypeptide chain is known as a _____

Answer 1

Gene

Question 2

In simplest terms, a gene is a ____ of ______ information

Answer 2

In simplest terms, a gene is a unit of hereditary information

Question 3

The total genomic information coded in the DNA of a typical cell in an organism is known as its ______

Answer 3

The total genomic information coded in the DNA of a typical cell in an organism is known as its genome

Question 4

There are _____ chromosomes in each cell

Answer 4

There are 46 chromosomes in each cell

Question 5

Along with its DNA molecule, a chromosome also contains a special class of proteins called:

(recall: beads on a string from molecular Biology)

Answer 5

Histones

Question 6

How are DNA molecules (with lengths “a thousand times greater than the diameter of the nucleus”) able to fit into the nucleus?

Answer 6

DNA molecules coil around clusters of Histones to form nucleosomes

Question 7

Most of the cells DNA is in the _____, whereas most protein synthesis occurs in the _____

Answer 7

Most of the cells DNA is in the nucleus, whereas most protein synthesis occurs in the cytoplasm

Question 8

The transfer of information from DNA to the site of protein synthesis is done by _____ molecules

Answer 8

The transfer of information from DNA to the site of protein synthesis is done by RNA molecules

Question 9

The process of transferring genetic infromation from DNA to RNA in the nucleus is known as:

Answer 9

Transcription

(info is transcribed from the master copy (DNA))

Question 10

The process that uses the coded information in RNA to assemble a protein in the cytoplasm is known as:

Answer 10

Translation

(Translated from nucleotide “language” to amino acid “language”)

Question 11

What is the Central Dogma

Answer 11

DNA —transcription→ RNA —translation→ Protein

Question 12

What does a molecule of DNA consist of?

Answer 12

two chains of nucleotides coiled around eachother to form a double helix

Question 13

What are the four nucleotide bases in DNA?

(group them into their respective sub-categories)

Answer 13

The purines:

1. Adenine
2. Guanine

(hint: Ag pure silver)

The pyrimidines:

1. Cytosine
2. Thymine

Question 14

In RNA, the nucleotide thymine is replaced by another nucleotide, what is its replacement?

Answer 14

Uracil

Question 15

Each “word” in the genetic language is only three letters long (composed from the four base pairs A, G, T, C) and, as such, is labelled a:

Answer 15

Triplet code

(AKA codon)

Question 16

How many three letter combinations are possible from the arrangement of the four DNA bases?

How does this compare to the number of different amino acids found in proteins?

Answer 16

64 possible 3 letter codes

20 amino acids

= each amino acid is usually specified by more than one 3-letter code

eg: CCA; CCG; CCT; and CCC all specify the AminoAcid (AA) glycine

Question 17

Only 61 of the possible 64 triplets are used to specify amino acids. The remaining three are called:

Answer 17

Stop signals (stop codon)

-think: a period at the end of a sentence

Question 18

Which type of RNA directly codes for the amino acid sequences of proteins?

Answer 18

Messenger RNA (mRNA)

Question 19

The class of RNA molecules that specifies the amino acid sequence of a protein and carries this message from DNA to the site of protein synthesis in the cytoplasm is known as

Answer 19

messenger RNA (mRNA)

Question 20

What enzyme joins together the aligned ribonucleotides during transcription

Answer 20

RNA polymerase

Question 21

DNA consists of two strands of _______ that run ______ to each other based on the orientation of their phosphate-sugar backbone

Answer 21

DNA consists of two strands of polynucleotides that run antiparallel to each other based on the orientation of their phosphate-sugar backbone

Question 22

Why aren’t isnt an RNA strand made from each DNA strand?

(reference a specific gene sequence and it’s relationship with RNA polymerase)

Answer 22

Because RNA polymerase only binds to DNA at specific points on a gene: adjacent to a sequence called the promoter - which is only found on the template strand of DNA

Question 23

The transcription of a gene begins when _______ binds to the ______ region of that gene

Answer 23

The transcription of a gene begins when RNA Polymerase binds to the promoter region of that gene

Question 24

What is the proteome of a cell?

What is it’s function?

Answer 24

the specific proteins expressed in a given cell at a particular time

-Determines the structure and function of a cell at that time

Question 25

A three base sequence in RNA that specifies one amino acid is called a :

Answer 25

Codon

Question 26

Each codon is complementary to a \_\_\_\_\_-base sequence of DNA

Answer 26

Each codon is complementary to a _three_-base sequence of DNA (eg the base sequence TAC in DNA corresponds to the codon AUG in transcribed RNA)

Question 27

The entire sequence of nucleotides in the template strand of a gene is transcribed into a complementary sequence of nucleotides known as the ________ or \_\_\_\_\_\_\_

Answer 27

The entire sequence of nucleotides in the template strand of a gene is transcribed into a complementary sequence of nucleotides known as the _primary RNA transcript_ or _pre-mRNA_

Question 28

Only certain segments on most genes actually encode sequences of amino acids. These regions are known as ______ and are separated by non-coding sequences of nucleotides known as \_\_\_\_\_\_

Answer 28

Only certain segments on most genes actually encode sequences of amino acids. These regions are known as _exons (expression regions)_ and are separated by non-coding sequences of nucleotides known as _introns_

Question 29

A class of very short RNA molecules called ______ are transcribed (in some cases) from noncoding DNA

Answer 29

A class of very short RNA molecules called _microRNAs_ are transcribed (in some cases) from noncoding DNA

Question 30

MicroRNAs are not translated into protein. What *is* there function?

Answer 30

MicroRNAs are not translated into protein, but rather, _Prevent the translation of specific mRNA molecules_

Question 31

Before passing into the cytoplasm, a newly formed primary RNA transcript must undergo \_\_\_\_\_\_

Answer 31

Before passing into the cytoplasm, a newly formed primary RNA transcript must undergo _splicing_

Question 32

Where does the transcription of ribosomal RNA (rRNA) occur?

Answer 32

Within the nucleolus

Question 33

Ribosomal proteins, like other proteins, are synthesized in the ______ from the mRNAs specific for them. These proteins then move back through the ______ to the nucleolus where they combine with the newly synthesized ______ to form two ribosomal subunits (one large and one small)

Answer 33

Ribosomal proteins, like other proteins, are synthesized in the _cytoplasm_ from the mRNAs specific for them. These proteins then move back through the _nuclear pores_ to the nucleolus where they combine with the newly synthesized _rRNA_ to form two ribosomal subunits (one large and one small)

Question 34

Free amino acids can't bind to the bases in mRNA codons by themselves, and must have assistance from the third major class of RNA: \_\_\_\_\_\_

Answer 34

Free amino acids can't bind to the bases in mRNA codons by themselves, and must have assistance from the third major class of RNA: _Transfer RNA (tRNA)_

Question 35

What is an anticodon?

Answer 35

The tRNA 3-letter code sequence that can base-pair with a three letter complementary codon on mRNA

Question 36

What are the three stages to translation?

Answer 36

1. Intitiation 2. Elongation 3. Termination

Question 37

A number of proteins known as ______ are required to establish an initiation complex in translation

Answer 37

A number of proteins known as _initiation factors_ are required to establish an initiation complex in translation

Question 38

Transcription of most genes is regulated by a class of proteins known as?

Answer 38

Transcription factors

Question 39

The transcription factors, along with accessory proteins, form a _______ at the promoter that is needed to carry out the process of _______ the ______ strands, removing any blocking _____ in the region of the promoter, activating the bound \_\_\_\_\_\_\_, and moving the complex along the \_\_\_\_\_\_\_

Answer 39

The transcription factors, along with accessory proteins, form a _Preinitation complex_ at the promoter that is needed to carry out the process of _separating_ the _DNA_ strands, removing any blocking _nucleosomes_ in the region of the promoter, activating the bound _RNA polymerase_, and moving the complex along the _template strand of DNA_

Question 40

The textbook states that rate of a protein's synthesis can be regulated at 3 points, list them

Answer 40

1. gene transcription into mRNA 2. the initiation of protein assembly on a ribosome 3. mRNA degradation in the cytoplasm