Term
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Definition
the instructions that tell the cell what to do
> Usually result in proteins
> study of metabolic defects provided evidence that genes lead to proteins |
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Term
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Definition
study of metabolic defects provided evidence that genes lead to proteins
> suggested that some metabolic disorers were caused by a blocked pathway (1909)
> inherited diseases were the result of the lack of an enzyme |
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Term
| 2 bad things about blockage in a pathway |
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Definition
> stops production of something we need
> may lead to the accumulation of something we don't want |
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Term
| George Beadle and Edward Tatum |
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Definition
| conducted experiment with bread mold, neurospora crassa, and demonstrated that different mutants (generated by x-rays) had the pathway of arginine (an amino acid) synthesis blocked at different steps. |
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Term
| Beadle and Tatum figured this out |
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Definition
deduced that the 3 different mutant types each lacked a different enzyme in the pathway which synthesizes arginine.
From these results, they formulated the one gene-one enzyme hypothesis |
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Term
Step one: DNA to RNA
This process is called transcription |
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Definition
> Transcription is the synthesis of RNA using DNA as a template
> The RNA is complementary to the DNA
> instead of A T, A bonds with U (Uracil) |
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Term
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Definition
| > RNA that is synthesized from a gene coding for a protein called |
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Term
Ø Differences between DNA and RNA:
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Definition
1. Sugar – deoxyribose (DNA) versus ribose (RNA)
2. Base – thymine (DNA) is replaced by Uracil (RNA) |
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Term
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Definition
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Term
| During transcription of a gene, only one strand (template strand) of the DNA’s two strands is read. Why? |
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Definition
| Different genes use different strands as the template strand. |
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Term
Step two: RNA to protein
> This process is called translation |
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Definition
Translation is the synthesis of a polypeptide directed by mRNA
Called translation because
** Converting the language of nucleic acids into the language of proteins
> 4 bases in nucleic acids
> 20 amino acids in proteins |
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Term
| Translation occurs on the ... |
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Definition
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Term
| During translation, proteins are synthesized according to the genetic message of sequential _______ in the mRNA |
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Definition
| codons (3 amino letters in a row) |
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Term
| Transfer RNA (tRNA) and ribosomal RNA (rRNA) |
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Definition
acts as the “interpreter” between the nucleotide “language” of mRNA and the amino acid “language” of proteins
In the genetic code, a triplet of nucleotides specifies an amino acid |
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Term
Dictated by the math, since there are 4 nucleotides and 20 amino acids
4 different nucleotides, combining as codons, which are 3-nucleotide sequences.
There are as many as ___ amino acids
But there are only ___, since
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Definition
64 (43);
20; each amino acid is usually encoded by more than one codon. |
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Term
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Definition
| is a three-nucleotide sequence in mRNA that specifies which amino acid will be added to a growing polypeptide or signals the termination of translation. |
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Term
> __ of the __ possible codons code for amino acids
> the remaining __ triplets signal the translation to start (start codon) and translation to stop (stop codon)
> Since there are only __ amino acids, more than one triplet can code for the same amino acid
> This relationship makes the code ______, or degenerate
> The codons usually differ only at the third position
> There is no ambiguity in the triplet code since a given triplet codes for one and only one amino acid |
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Definition
> 60 of 64
> 4
> 20
> redundant |
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Term
| RNA polymerase binds to the ________ region of DNA near the beginning of a ____, separating the double helix near the promoter |
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Definition
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Term
RNA polymerase travels along the DNA template strand, catalyzing the addition of _____________ into an RNA molecule.
> The nucleotides in the RNA are __________ to the template strand of the DNA |
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Definition
ribose nucleotides
> complementary |
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Term
At the end of a gene, RNA polymerase encounters a sequence of DNA called a __________.
> RNA polymerase detaches from the DNA and releases the RNA molecule. |
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Definition
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Term
After termination, the DNA completely rewinds into a double helix.
> The RNA molecule is free to move from the ______ to the ________ for translation, and RNA polymerase may move to another gene and begin transcription once again, or it can even re-bind the same promoter and transcribe the same gene again. |
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Definition
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Term
_______ is the RNA-directed synthesis of polypeptides
> During this, proteins are synthesized according to the genetic message of sequential codons in the mRNA. |
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Definition
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Term
> The sequence of nucleotides present in the DNA is reflected by the sequence in the RNA.
AND
> The sequence of nucleotides in a mRNA determines the sequence of ________ |
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Definition
amino acids
AND
> The sequence of amino acids determines the protein. |
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Term
The ribosome is where the _______________
The ribosome coordinates the pairing of tRNA anticodons with ______ |
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Definition
proteins are built.
mRNA codons |
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Term
Ribosomes have 2 sites:
>___site – holds the tRNA with the polypeptide chain attached.
> ___ site – holds the tRNA when the next amino acid to be added |
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Definition
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Term
| The ________ holds all the components together as enzymes transfer the next amino acid to the growing polypeptide |
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Definition
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Term
| _____acts as the “interpreter” between the nucleotide language of mRNA and the amino acid language of proteins. |
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Definition
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Term
In part of this role as “interpreter,” the tRNA must “read” the mRNA.
This is accomplished by the ______portion of tRNA |
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Definition
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Term
| The other portion of the tRNA’s role as “interpreter” is to transfer the correct amino acid from the _____________ to the ribosome for protein sythesis. |
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Definition
| cytoplasmic pool of amino acids |
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Term
Protein sythesis occurs in three stages:
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Definition
1. Initiation
2. Elongation
3. Termination |
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Term
1. The initiation complex binds to an mRNA molecule.
The methionine (met) tRNA anticodon (UAC) base-pairs with the ______ (AUG) of the mRNA. |
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Definition
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Term
2. Elongation
The next tRNA occupies the A site and the anticodon hydrogen bonds to the codon of the mRNA
Peptide bond formation |
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Definition
> The methionine from the initiator tRNA forms a peptide bond with the amino acid on the tRNA at the A site.
> This leaves the tRNA at the P site with no amino acid, and the tRNA at the A site with a dipeptide attached
> The tRNA vacates the P site
> The ribosome moves one codon down the mRNA
This translocates the tRNA (with the growing peptide) form the A site to the P site.
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Term
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Definition
the mRNA reaches a stop codon; UAA, UAG, or UGA
Stop codon is a tiplet codon that signals the end of translation. |
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Term
| ________ can affect the function of a protein. |
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Definition
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Term
| _________ are permanent changes in the DNA that can involve large chromosomal regions or a single nucleotide pair. |
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Definition
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Term
| _________ are mutations limited to one or two nucleotides in a single line |
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Definition
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Term
| __________ is the insertion of one or more nucleotide pairs into a gene |
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Definition
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Term
| _______ is the deletion of one or more nucleotide pairs from a gene |
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Definition
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Term
| The _______ is the sequence of activities that occurs between one cell division and the next. |
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Definition
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Term
Cell division is divided into 3 stages:
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Definition
o Growth
o Renewal and Repair
o Reproduction |
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Term
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Definition
the process in which the genetic information of a cell is passed along to the next generation of cells.
o Involves the division of a parent cell into 2 daughter cells.
o Characteristics of cell division
§ Replication of DNA
§ Equal distribution of DNA to opposite ends of the dividing cell
§ Separation into 2 daughter cells |
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Term
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Definition
Reproduction in which offspring are formed from a single parent, rather than through a fusion of gametes (sperm and egg) as in sexual reproduction.
> Asexual reproduction involves only one parent. Produces genetically identical offspring. |
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Term
Bacteria reproduce by binary fission
Binary fission is ...
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Definition
| a prokaryotic cell division, which literally means “splitting in two” |
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Term
| What happens during binary fission: |
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Definition
> the circular DNA double helix is attached to the plasma membrane at one point.
> The DNA replicates and the two DNA double helices attach to the plasma membrane at nearby points.
> The plasma membrane between the attachment points enlarges, pushing them farther apart.
> Once the cell has doubled in size, the plasma membrane rapidly grows inward between the 2 DNA attachment sites.
> The parent cell divides into 2 daughter cells, each containing a complete chromosome.
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Term
| If the organism is single-celled then a cell cycle can be the same as the ______ |
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Definition
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Term
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Definition
| a well-ordered sequence during which the cell divides, grows, and prepares to divide again. |
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Term
| During the cell cycle, interphase alternates with ______ |
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Definition
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Term
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Definition
| the period of the cell cycle when the cell is not dividing. |
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Term
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Definition
o Non-dividing phase.
o During this time, the cell is acquiring nutrients from its environment, growing, and replicating its DNA
o Interphase makes up about 90% of the cell cycle
o High metabolic activity
o Chromosomes and organelles are duplicated |
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Term
| Example of chromosomes and organelles being duplicated |
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Definition
§ Ex. Human skin cells divide about once a day.
These skin cells spend about 22 hours in interphase.
Consists of 3 phases: G1 phase, S phase, and G2 phase. |
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Term
G1 to G0 phase
o Some cells can exit G1 and enter G0 phase |
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Definition
During G0, cells do not replicate their DNA and do not divide.
> During G0, cells do not replicate their DNA and do not divide.
> Many cells undergo a process called differentiation in G0 where the external signals that it receives will determine what type of cell it becomes.
> Many differentiated cells, including most of those in your heart, eye, and brain will stay in G0 for the rest of your life.
> Most of these cells do NOT divide. |
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Term
| Cell division consists of nuclear division and cytoplasmic division |
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Definition
Mitosis is the division of the cell nucleus
§ During this process the DNA is equally distributed into 2 daughter nuclei. |
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Term
| The division of the nucleus is usually followed quickly by cytokinesis |
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Definition
| Cytokinesis is the divisino of the cytoplasm that forms 2 separate daughter cells, each containing a single nucleus. |
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