4 Basic Genetic Mechanisms Flashcards
it is important in the normal functioning of the body.
synthesis of proteins
-is the basis for the synthesis of proteins.
-It serves as the template to direct its replication and also provides the blueprint for the synthesis of proteins by its ability to direct the process of transcription and translation.
-consists of a chain of four kinds of nucleotides based on the type of nitrogenous bases.
DNA
is composed mostly of chromosomes, structures that provide the inherited and individual characteristics of an animal.
nucleus
DNA is made up of
two long polynucleotide chains.
Each nucleotide is composed of
one molecule of phosphoric acid
one molecule of deoxyribose
one of the four bases.
In the nucleus, the cell’s machinery copies the gene sequence into messenger RNA (mRNA), a molecule that is similar to DNA. Like DNA, mRNA has four nucleotide bases - but in mRNA, the base uracil (U) replaces thymine (T)
TRANSCRIPTION
-The protein-making machinery, called the ribosome, reads the mRNA sequence and translates it into the amino acid sequence of the protein. The ribosome starts at the sequence AUG, then reads three nucleotides at a time. Each three nucleotide codon specifies a particular amino acid. The “stop” codons (UAA, UAG and UGA) tell the ribosome that the protein is complete.
-is the formation of the polypeptide from mRNA.
TRANSLATION
This process is described to be semiconservative because each strand of a DNA double helix serves as a template for the synthesis of a complementary strand of DNA and each new DNA molecule consists of one old strand and one new strand.
DNA Replication
DNA replication starts with ____(what enzyme) unwinding of two strands by ____ formed between the complementary bases.
DNA helicase
breaking hydrogen bonds
what keeps DNA strands from binding again the whole topoisomerase preventing the supercoiling of the single strand of DNA.
Single-stranded binding proteins (SSBPs)
what is the enzyme that binds to the single-strand DNA attaches free nucleotides into a new strand of DNA based on complementary base pairing in a strictly 5’ to 3’ direction.
DNA polymerase
*DNA Replication
The unwinding of the double-stranded DNA forms two strands of DNA in two different directions called the
leading strand
lagging strand
*DNA Replication
the new strand is assembled continuously
leading strand
*DNA Replication
What do you call the new DNA strand that is assembled in many pieces (Okazaki fragments)
lagging strand,
enzyme that seals the pieces of a lagging strand
DNA ligase
is a segment of a DNA molecule that contains the information required for the synthesis of a functional biological product (protein or RNA).
gene
-sugar of a slightly different composition used in the formation of RNA
-contains an extra hydroxyl ion appended to the ribose ring structure.
ribose
In RNA, Thymine is replaced by another pyrimidine, ____
uracil
Four different types of RNA
Messenger RNA
Transfer RNA
Ribosomal RNA
MicroRNA (miRNA)
*Type of RNA
carries the genetic code to the cytoplasm for controlling the type of protein formed. Long, single RNA strands that are suspended in the cytoplasm are composed of several hundred to several thousand RNA nucleotides in unpaired strands; they contain codons that are exactly complementary to the code triplets of the DNA genes.
Messenger RNA,
*Type of RNA
-transports activated amino acids to the ribosomes to be used in assembling the protein molecule; a carrier to transport specific types of amino acid to the ribosomes
-recognizes a particular codon on the messenger RNA
-a small molecule with a cloverleaf appearance
-Anticodon:
Transfer RNA,
*Transfer RNA
specific code in the transfer RNA that allows it to recognize a specific codon (a triplet of nucleotide bases combine loosely by hydrogen bonding with the codon).
Anticodon:
*Type of RNA
along with about 75 different proteins, forms ribosomes, the physical and chemical structures on which protein molecules are assembled. This constitutes about 60 percent of the ribosome manufacturing plant.
Ribosomal RNA,
*Type of RNA
are single-stranded RNA molecules of 21 to 23 nucleotides that can regulate gene transcription and translation acts to decrease gene expression.
MicroRNA (miRNA),
-this starts when RNA polymerase and regulatory proteins attach to a promoter (a specific binding site in DNA close to the start of a gene).
-process of a nucleotide sequence of a gene used to synthesize a complementary strand of RNA.
-is the formation of mRNA from a single DNA strand.
Transcription
What is the enzyme that moves over the gene in a 5’ to 3’ direction, unwinds the DNA helix, reads the base sequence, and joins free RNA nucleotides into a complementary strand of mRNA.
RNA polymerase
In transcription, each transcript is an RNA copy of a
gene
is a sequence of three mRNA nucleotides that codes for a specific amino acid. The order in mRNA determines the order of amino acids in a polypeptide chain.
codon
The process of translation includes the role of what types of RNA
tRNAs and rRNA.
*Translation, type of RNA
____ has an anticodon complementary to an mRNA codon, and a binding site for the amino acid specified by that codon.
tRNA
Translation occurs in the cytoplasm of cells and has three stages which are
Initiation
Elongation
Termination
*stage of translation
The small ribosomal subunit binds to the start of the mRNA sequence. Then a tRNA molecule carrying the amino acid methionine binds to what is called the start codon of the mRNA sequence. The start codon in all mRNA molecules has the sequence AUG and codes for methionine. Next, the large ribosomal subunit binds to form the complete initiation complex.
Initiation.
*Stage of translation
The ribosome assembles a polypeptide chain as it moves along the mRNA. Each corresponding amino acid is added to the growing chain and linked via a bond called a peptide bond. This continues until all of the codons are read.
Elongation.
*Stage of translation
When the ribosome encounters a stop codon, polypeptide synthesis ends. This occurs when the ribosome reaches a stop codon (UAA, UAG, and UGA). Since there are no tRNA molecules that can recognize these codons, the ribosome recognizes that translation is complete. The new protein is then released, and the translation complex comes apart. Release factors bind to the ribosome. Enzymes detach the mRNA and polypeptide chain from the ribosome.
Termination.
The polypeptides synthesized from translation will undergo ____ to produce an active or final form of proteins.
post-translational modification
-If the nucleotide sequence of gene changes, it may result in an altered gene product, with harmful effects.
-are small-scale changes in the nucleotide sequence of a cell’s DNA that alter the genetic code.
Mutation
Common mutations:
base-pair mutation
deletion
insertion
type of mutation that may result in a premature stop codon or a different amino acid in a protein product.
base-pair substitution
type of mutation which can cause the reading frame of mRNA codons to shift, changing the genetic message.
deletion or insertion
example of a disorder caused by base-pair mutation
sickle-cell anemia.
example of a disorder caused by deletion or insertion mutation
Huntington’s disease.
Causes of mutation:
transposable elements (segments of DNA that can insert themselves anywhere in chromosomes),
spontaneous mutations (uncorrected errors in DNA replication),
harmful environmental agents such as ionizing radiation, UV radiation, and chemicals.
two types of nucleic acids found in the
body?
DNA and RNA
