chapter 7 the blueprint of life, from dna to protein Flashcards
what is genetics?
the science of heredity
the science of heredity
genetics
molecular biology
the science dealing with DNA, and protein synthesis
the science dealing with DNA, and protein synthesis
molecular biology
Molecular biology:
The total DNA contained in the cell
genome
what is a genome
a total DNA contained in the cell
true or false molecular biology :
consist of the chromosomes and any plasmids
true
Molecular biology:
is it false that chromosomes does not contain the genes
Yes it is in fact false, because chromosomes contain the gene
define gene
sections of DNA that code for a functional product
sections of DNA that code for a functional product
gene
define what DNA is
macromolecule made of nucleotides
Each nucleotide in DNA has….
1) nitrogenous base ( AT,CG)
2) Sugar (deoxyribose)
- numbered 1’-5’
3) phosphate
Is it true that DNA forms a double helix?
yes it is true
So as we know DNA forms a double helix bonds:
Two strands are held together by _____ between ____
hydrogen bonds, and in between bases
The base pairing rules in DNA, name it
AT
CG
True or false are the strands in the DNA are complementary?
True
Define what the Strands of DNA are complementary mean
sequence of one strand determines the sequence of the other
Nucleotides in the DNA are linked together by what?
covalent phosphodiester bonds
true or false.
5’ carbon of one nucleotide is joined to 3’ carbon of the next nucleotide, with a covalent between them
false, it is not a covalent between them but rather a phosphate between them
We usually consider DNA in the _________
5’3 direction
what is the starting in the DNA and finishing end?
starting 5’ end and finishing at 3’ end
Two strands of DNA run _____
antiparallel
The flow of genetic information
name the 3
- cell replication
2.gene expression
3.recombination
define cell replication
DNA is copied before cell division
dna is copied before cell division
cell replication
Define gene expression
DNA is used to make proteins
DNA is used to make proteins
Gene expression
Define what recombination mean
DNA can flow between two different bacterial cells
DNA can flow between two different bacterial cells
recombination
Dna replication define it
one parental double stranded DNA molecule is used to make 2 identical double stranded DNA molecules
true or false.
DNA replciation:
because the strands are not complementary, it cannot be used to as a template?
false, it can be used as a template
Now we are aware that strands are complementary and because of that…
one strands can act as a template for synthesis of the other strands
DNA polymerase….
reads the order of nucleotides in the template strands to make a complementary new strand
Name the first step of DNA replication
- A small segment of the dsDNA and the strands unwinds and the strands are separated
- which forms a replication fork
- each separated strand serves asa template for synthesis of a complementary strand
A short RNA primer is produced by the enzyme : Primase
serves as a starting site for nucleotides to form new strand of DNA
true or false.
A short RNA primer is produced by the enzyme:Primase
true
What is the second step of DNA replication
- Synthesis of the Leading strand
- Dna pol can only synthesize DNA in one direction = 5’ -> 3’
- template must be read in the 3’-> 5’ direction
-follows the replication fork
-synthesis of the leading strand is continous in the 5’ to 3’ direction
name the third step of dna replication
3.Synthesis of the lagging strand
- Dna polymerase can only make DNA in the 5’ to 3’ direction
- but the secnd strand must made in the opposite diretion
Dna polymerase synthesizes small fragments of DNa “ okazaki fragments
- made in the 5’ to 3’ direction
-afterwards , the RNA primers are removed and the fragments are joined together by enzyme DNA ligase.
What are the two parts of gene expression
translation and transcription
what is transcription
information stored in DNA is copied into RNA
what is translation
information in RNA is decoded to make protein
name the characteristics of transcription
synthesis of RNA from a DNA template
- sequence is complementary to a gene
- except: it contains U instead of T
True or false: in transcription synthesis of DNA from a RNA template is what is occuring
False, it is the opposite
What are the three types of RNA
Messenger RNA
Ribosomal RNA
Transfer RNA
describe what Messenger RNA is:
carries information for making specific protein
describe what Ribosomal RNA mean:
forms part of ribosome
describe what Transfer RNA mean:
transports specific amino acids for protein synthesis
what are the steps in transcription
initiation
elongation
termination
carries information for making specific amino acid
mRNA
forms a part of ribosome
rRNA
transports specific amino acids for protein synthesis
tRNA
define initiation in transcription
RNA polymerase binds to a gene at a specific site called the promoter
- seperates (melts) the two strands
Only one strand is copied- the template
the template is read in the 3’–>5’ direction so that RNA can be made in the 5’–>3’ direction
describe elongation
RNA polymerase moves along the template synthesizing new RNA
- allows the DNA to rewind behind it
describe termination
When RNA polymerase encounters the terminator (end of the gene) it falls off the template and releases the newly synthesized RNA.
is it true: that RNA polymerase binds to the gene site called the promoter
yes it is true
the genetic code:
information in mRNa must be———-
translated to make proteins
the genetic code is organized into sets of _____ , also known as
3 sets of nucleotides - also known as codons
True or false: genetic code:
each codon does not specifies an amino acid, no specification is needed to be added during protein synthesis
this is false, each codon specifies an amino acid to be added during protein synthesis
True or false: genetic code:
sequence of codons in an tRNA determines sequence of amino acids in the protein
no this is not the job of tRNA, this is the job of mRNA therefore it is false.
what are the three codons that specify stop codon :
UAA, UAG, UGA
what does stop codon mean?
it signals the end of protein synthesis
What are the steps in translation
1.initiation
2.elongation
3.termination
true or false: transcription and translation holds the same steps , however they differ in the functions
this is in fact true
Initiation in translation:
- a ribosome assembles on the mRNA
a tRNA carrying the amino acid formyl methionine enters the P site
a tRNA carrying a second amino acid enters the ribosome
Specified by the codon in the A site
The ribosome joins the amino acids together by a peptide bond
elongation in translation
the ribosome moves a distance of one codon down the mRNA
- the next codon is now place in the A site
the correct tRNA enters the A site, bringing with it the next amino acid to be added
the amino acid is joined to the chain
forms a polypeptide
elongation continues until “ a stop codon” is reached
termination in translation:
when a stop codon enters the A site, the ribosome dissembles and releases the polypeptide
the polypeptide is folded into the correct shape and becomes a protein
the ribosome can initiate translation of another mRNA
