Chapter 3 section B: Protein Synthesis, Degradation, and Secretion Flashcards
A sequence of DNA nucleotides containing the information that specifies the amino acid sequence of a single polypeptide chain is known as a _____
Gene
In simplest terms, a gene is a ____ of ______ information
In simplest terms, a gene is a unit of hereditary information
The total genomic information coded in the DNA of a typical cell in an organism is known as its ______
The total genomic information coded in the DNA of a typical cell in an organism is known as its genome
There are _____ chromosomes in each cell
There are 46 chromosomes in each cell
Along with its DNA molecule, a chromosome also contains a special class of proteins called:
(recall: beads on a string from molecular Biology)
Histones
How are DNA molecules (with lengths “a thousand times greater than the diameter of the nucleus”) able to fit into the nucleus?
DNA molecules coil around clusters of Histones to form nucleosomes
Most of the cells DNA is in the _____, whereas most protein synthesis occurs in the _____
Most of the cells DNA is in the nucleus, whereas most protein synthesis occurs in the cytoplasm
The transfer of information from DNA to the site of protein synthesis is done by _____ molecules
The transfer of information from DNA to the site of protein synthesis is done by RNA molecules
The process of transferring genetic infromation from DNA to RNA in the nucleus is known as:
Transcription
(info is transcribed from the master copy (DNA))
The process that uses the coded information in RNA to assemble a protein in the cytoplasm is known as:
Translation
(Translated from nucleotide “language” to amino acid “language”)
What is the Central Dogma
DNA —transcription→ RNA —translation→ Protein
What does a molecule of DNA consist of?
two chains of nucleotides coiled around eachother to form a double helix
What are the four nucleotide bases in DNA?
(group them into their respective sub-categories)
The purines:
- Adenine
- Guanine
(hint: Ag pure silver)
The pyrimidines:
- Cytosine
- Thymine
In RNA, the nucleotide thymine is replaced by another nucleotide, what is its replacement?
Uracil
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:
Triplet code
(AKA codon)
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?
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
Only 61 of the possible 64 triplets are used to specify amino acids. The remaining three are called:
Stop signals (stop codon)
-think: a period at the end of a sentence
Which type of RNA directly codes for the amino acid sequences of proteins?
Messenger RNA (mRNA)
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
messenger RNA (mRNA)
What enzyme joins together the aligned ribonucleotides during transcription
RNA polymerase
DNA consists of two strands of _______ that run ______ to each other based on the orientation of their phosphate-sugar backbone
DNA consists of two strands of polynucleotides that run antiparallel to each other based on the orientation of their phosphate-sugar backbone
Why aren’t isnt an RNA strand made from each DNA strand?
(reference a specific gene sequence and it’s relationship with RNA polymerase)
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
The transcription of a gene begins when _______ binds to the ______ region of that gene
The transcription of a gene begins when RNA Polymerase binds to the promoter region of that gene
What is the proteome of a cell?
What is it’s function?
the specific proteins expressed in a given cell at a particular time
-Determines the structure and function of a cell at that time
A three base sequence in RNA that specifies one amino acid is called a :
Codon
Each codon is complementary to a _____-base sequence of DNA
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)
The entire sequence of nucleotides in the template strand of a gene is transcribed into a complementary sequence of nucleotides known as the ________ or _______
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
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 ______
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
A class of very short RNA molecules called ______ are transcribed (in some cases) from noncoding DNA
A class of very short RNA molecules called microRNAs are transcribed (in some cases) from noncoding DNA
MicroRNAs are not translated into protein. What is there function?
MicroRNAs are not translated into protein, but rather, Prevent the translation of specific mRNA molecules
Before passing into the cytoplasm, a newly formed primary RNA transcript must undergo ______
Before passing into the cytoplasm, a newly formed primary RNA transcript must undergo splicing
Where does the transcription of ribosomal RNA (rRNA) occur?
Within the nucleolus
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)
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)
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: ______
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)
What is an anticodon?
The tRNA 3-letter code sequence that can base-pair with a three letter complementary codon on mRNA
What are the three stages to translation?
- Intitiation
- Elongation
- Termination
A number of proteins known as ______ are required to establish an initiation complex in translation
A number of proteins known as initiation factors are required to establish an initiation complex in translation
Transcription of most genes is regulated by a class of proteins known as?
Transcription factors
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 _______
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
The textbook states that rate of a protein’s synthesis can be regulated at 3 points, list them
- gene transcription into mRNA
- the initiation of protein assembly on a ribosome
- mRNA degradation in the cytoplasm
