Molecular Genetics (chapter 18) Flashcards
Frederick Griffith
studied pathogenic bacteria, discovered the transforming principle
Friedrich Mieshcer
first to isolate DNA from the nucleus of white blood cells
what are nucleotides made up of?
a sugar, a phosphate and one of the 5 nitrogen nitrogen-containing bases
what is the transforming principle? (Frederick Griffith)
a substance that could be transferred from a non living to living cells, will cause the living cell to show or display characteristics of the non living cell.
what is Chargaffs rule?
that the nitrogen bases for DNA are always paired A=T and G=C
which is single stranded and which is double stranded? (Purines and Pyrimidines)
Purine is double
Pyrimidines are single
which nitrogen bases in DNA are purines?
adenine and thymine - this means that they are two-carbon nitrogen ring bases
which nitrogen bases in DNA are pyrimidines?
guanine, cytosine, and uracil - this means that they are one-carbon nitrogen ring bases
what are considered the “backbones” of the double helix and what is considered the “ladder”?
the backbones are classified as the sugar and the phosphate, while the nitrogen bases make the ladder.
what is the sugar in nucleotides called?
deoxyribose (5 carbon sugar)
what are the 4 nitrogen bases only found in DNA?
adenine, thymine, guanine and cytosine
what does RNA contain that differs from DNA?
uracil in place of thymine (NO T’S IN RNA’S)
why do DNA strands run antiparallel to one another?
one represents the leading strand, while the other represents the lagging, which comes into play during dna replication
what phase does DNA replication take place during in the cell?
the synthesis phase
when does the process of DNA replication begin?
when the strand becomes too large, therefore making it difficult for the cell to do it’s job properly
DNA contains one strand of the ______ DNA molecule and one new ________ strand
original, parent
what are absolutely required to make DNA replication possible?
enzymes
a group of unwinding enzymes called ______ bind to the DNA at the replication origin and unravel the double helix
helicase
______ is used to make a short segment of RNA primers which is used to get the replication process started
primase
_________ is responsible for elongation of the new DNA strand at the replication fork
DNA polymerase
what direction does the leading strand run from?
5’ to 3’ which is also continuous
what direction does the lagging strand run from?
3’ to 5’ which is noncontinuous and grows in fragments called Okazaki fragments
__________ also removes the RNA primers and replaces with DNA to then fill the gaps between the okazaki fragments
DNA polymerase
what are mistakes in DNA replication that are NOT repaired?
mutations
proteins are made up of subunits called what?
amino acids
the order of nucleotides in DNA is known as what?
genetic code
short segments of protein are called what?
polypeptides
how many nucleotide bases are used to define/make up an amino acid?
3
The Central Dogma
a DNA strand undergoes transcription into a RNA and then undergoes translation into a new code that will make up a protein
DNA does not leave the nucleus, therefore will need a copy of the DNA to make proteins, what is this called?
messenger RNA (mRNA)
the template strand in transcription is also known as what?
RNA polymerase
in transcription, when it comes to RNA what are the new pairings of the nucleotide bases?
adenine=uracil, guanine=cytosine
in RNA the sugar backbone is no longer deoxyribose, instead, it is what?
ribose
_____ is used to make RNA
RNA polymerase
DNA contains sections called introns and exons, what are they for?
exons: protein codings
introns: non protein codings
the mRNA is moved to the _______ where it is used for _______
cytoplasm, protein synthesis
what is translation for?
the process in which proteins are created using the genetic code that was copied onto the mRNA during transcription
what is a codon or triplet?
the sequence of 3 nitrogen bases making up a genetic code, also known as a triplet
where does translation take place?
ribosomes
what is an anticodon?
sequence of 3 nucleotides in tRNA molecules to compliment a codon in mRNA
what do anticodons do?
they ensure that the correct amino acid is inserted onto the polypeptide
what are point mutations?
a chem. change that involves one or a few nucleotides in a single gene
what are chromosomal mutations?
ones that affect an entire chromosome or large parts of a chromosome
what are mutagens? (two types)
there are chemical and physical, and are agents that interact with DNA to cause mutations
what is recombinant DNA?
contains dna from 2 different sources
what is DNA cloning?
the process of making a genetically identical copy of a gene or organism
what is the role of ligase in DNA replication?
to glue fragments of dna together to create a continuous strand
what are restriction enzymes and where are they found?
they are usually found in bacteria. used as defence mechanisms, and their role is to cut up intruding DNA from other organisms
what is the role of ligase in the context of restricting enzymes?
they are used to rejoin the sticky ends of DNA that were cut up by restriction enzymes
what is a polypeptide?
a chain of amino acids
what is point mutation?
a chemical change that involves one or a few nucleotides in a single gene
what types of point mutation fall under substitution?
silent, missense and nonsense
what types of point mutation fall under insertion and deletions?
addition or loss of one or more nucleotide pairs in a gene
what is silent mutation?
they have no effect on the protein they are coded for
what is missense point mutation?
mutations which will code for an amino acid that make sense, but not necessarily the right sense
what are nonsense mutations?
if the substitution changes the amino acid codon into a stop signal, this results in non functional proteins.
define recombinant DNA
containing DNA from two different sources
define DNA cloning
the transfer of DNA fragments from one organism to a self replicating genetic element such as bacterial plasmid
