Genetics Part II Flashcards
describe RNA’s structure
BASES:
- CYTOSINE
- GUANINE
- ADENINE
- URACIL (takes THYMINE’S PLACE)
SUGAR:
- RIBOSE
PHOSPHATE GROUPS
what are the THREE TYPES OF RNA and their FUNCTIONS?
**these are all NECESSARY to DO PROTEIN SYNTHESIS
rRNA:
RIBOSOMAL RNA–part of the STRUCTURE of RIBOSOMES
tRNA:
TRANSFER RNA–functions as HELPTER to bring CORRECT AMINO ACIDS to RIBOSOME to build NEW PROTEINS
mRNA:
MESSENGER RNA–carries the CODE from DNA to RIBOSOMES–where PROTEINS ARE MADE
describe TRANSCRIPTION. the importance of RNA POLYMERASE?
what is TRANSCRIPTION?
- the SYNTHESIS of COMPLEMENTARY STRAND of RNA from the DNA TEMPLATE
- only reads INDIVIDUAL GENES, not the ENTIRE GENOME
**DNA CANNOT BE READ DIRECTLY by the protein-making machine :(
- needs an INTERMEDIARY!!! which is mRNA
RNA POLYMERASE:
- uses DNA and basically copies/transcribes information into mRNA
- uses one of the DNA strands (template/antisense strand) as a TEMPLATE–creation of a COMPLEMENTARY RNA MOLECULE
what are the THREE STEPS OF TRANSCRIPTION?
- INITIATION
- RNA POLYMERASE binds to a specific site on the DNA known as the PROMOTER
- begins to UNWIND THE DNA STRANDS
PROMOTER:
a sequence of DNA that is RECOGNIZED by the RNA POLYMERASE–specific to that POLYMERASE
- ELONGATION
- where the RNA NUCLEOTIDES are now ADDED - TERMINATION
- RNA SYNTHESIS continues on until the RNA POLYMERASE reaches a site on the end called the TERMINATOR
definition of TRANSLATION
the process where the RIBOSOMES read the mRNA SEQUENCE and make a PROTEIN based on the SEQUENCE
nucleotide pairings —-> amino acids (within a PROTEIN)
describe the GENETIC CODE
this is where mRNA begins to STORE INFORMATION about which AMINO ACIDS need to get incorporated into POLYPEPTIDE CHAINS to make a PROTEIN within form of CODONS
definition of CODONS
groups of 3 nucleotides that code for a PARTICULAR AMINO ACIDS
- together create in sequence form the GENETIC CODE
describe the possible COMBINATIONS within our GENETIC CODE + what is REDUNDANCY?
COMBINATIONS:
have over 64 POSSIBLE PERMUTATIONS/COMBINATIONS of these three letter nucleotide sequences that are made from our FOUR NUCLEOTIDES (A,C,G,U)
**ACTUALLY :o we only have 20 SOLID AMINO ACID CODONS (PRIMARY)–we just have NUMEROUS CODONS FOR VARIOUS AA’s
this is known as REDUNDANCY
CODONS/COMBINATIONS (61):
- code for actual AMINO ACIDS
(1 of them is our START CODON–MET-AUG)
NONSENSE CODONS (3):
- code for a STOP-CODON which signals the END OF A PROTEIN MOLECULE
- UAA
- UAG
- UGA
describe tRNA and its role with ANTICODONS
tRNA:
specific RNA MOLECULES that help DECODE a MESSENGER RNA (mRNA) sequence into a PROTEIN
ANTICODONS:
sequence that can RECOGNIZE and BIND to the COMPLEMENTARY mRNA CODON–has an attached end with CORRESPONDING AMINO ACID
define the SHINE-DELGARNO SEQUENCE
SHINE-DELGARNO SEQUENCE:
- specific RIBOSOME BINDING SITE
- ribosomes begin to BIND mRNA at this sequence– “reads” the CODONS and inserts the appropriate AMINO ACID
**again remember TRANSLATION starts at the AUG START CODON and its respective STOP CODONS
describe the TRANSLATION PHASES
- all components form together to start TRANSLATIONS
- RIBOSOME is now ASSEMBLED–tRNA with the FIRST AMINO ACID starts at the AUG START CODON of mRNA (cont. as second tRNA begins to approach)
- SECOND PAIRING OCCURS with second codon (mRNA) and second amino acid (tRNA)
**AMINO ACIDS joined together by PEPTIDE BONDS within the P SITE - SECOND PAIRING MOVES into P (pairing) SITE, THIRD PARING MOVES into A (arrival) SITE, and FIRST PAIRING MOVES into E (exit) SITE :)
**cycle continues with each pairing and amino acids joining with PEPTIDE BONDS –until it eventually grows into a POLYPEPTIDE CHAIN
- ribosome reaches a STOP-CODON–products of a new RELEASED POLYPEPTIDE which forms a PROTEIN
describe what happens in terms of BACTERIAL (PROKARYTOIC) genetic coding
both TRANSCRIPTION and TRANSLATION occur at the SAME TIME–SIMULTANEOUSLY
describe what happens in terms of EUKARYOTIC genetic coding
TRANSCRIPTION:
- this occurs within the NUCLEUS
mRNA has to go from NUCLEUS to CYTOPLASM
EUKARYOTIC GENES:
- have specific NON CODING REGIONS: known as INTERONS
RNA POLYMERASE–continues to transcribe with INTERONS within our PRIMARY RNA TRANSCRIPT
SPLICING:
- INTERONS are REMOVED and SPLICED OUT–in order to make final mRNA
describe overview of REPLICATION, TRANSCRIPTION, and TRANSLATION
REPLICATION:
- purpose; MAKE IDENTICAL COPIES of DNA
- location; NUCLEUS (E), CYTOPLASM (P)
TRANSCRIPTION:
- purpose; MAKE RNA
- location; NUCLEUS/NUCLEOLUS (E), CYTOPLASM (P)
TRANSLATION:
- purpose; MAKE PROTEINS from RNA
- location; all within CYTOPLASM of the RIBOSOME
definition of regulation of genetic expression
the production of protein from RNA
definition of CONSTITUTIVE EXPRESSION
where EXPRESSION LEVEL is RELATIVELY CONSTANT (housekeeping genes)
- typically have most GENES within distinction > 60%
example: GLYCOLYSIS
**specific material that is always needed at a CONSTANT RATE within our BODIES
definition of REGULATED EXPRESSION
expression level that VARIES UNDER DIFFERENT CONDITIONS
have TWO TYPES;
1. INDUCTION
induced–the product is not made until NECESSARY
2. REPRESSION
repressed–continuously makes product until UNNECESSARY
definition of OPERONS
number of GENES that are CONTROLLED COLLECTIVELY by ONE PROMOTER
–often occurs PRIMARILY within PROKARYOTES
describe the LAC OPERON
a type of INDUCIBLE OPERON–induced within the PRESENCE of LACTOSE
- has specific genes for the TRANSPORT and METABOLISM of LACTOSE
if there is GLUCOSE ABSENCE:
- allows for the EFFECTIVE DIGESTION OF LACTOSE (since glucose is the PREFERRED CARBON SOURCE)
what are the THREE GENES within LACTOSE OPERON?
LAC Z:
beta-galactosidase; cleaves LACTOSE to GLUCOSE and GALACTOSE
LAC Y:
beta-galactosidase permase; enables TRANSPORT OF LACTOSE into the CELL
LAC A:
transacetylase
describe CATABOLITE REPRESSION
**again reminder, GLUCOSE is the PREFERRED CARBON SOURCE for most bacteria
LAC OPERON:
use of a TWO PART CONTROL MECHANISM that ensures cell is producing the NECESSARY ENZYMES ENCODED by the LAC OPERON ONLY
CATABOLITE REPRESSION:
seen within PRESENCE OF GLUCOSE–has CATABOLITE ACTIVATOR PROTEIN (CAP) helps in the PRODUCTION OF LAC OPERON ENZYMES–system stays INACTIVE until further notice
IF GLUCOSE IS PRESENT–CAP IS NOW ACTIVE and ACTIVATES the TRANSCIPTION of the LAC OPERON
describe the TRYPTOPHAN OPERON
a type of REPRESSIBLE OPERON –its own structural genes are TRANSCRIBED till they are TURNED OFF
- we have FIVE GENES involved witihin TRYPTOPHAN SYNTHESIS
- this has to be REGULATED; if we do have TRYPTOPHAN PRESENT–genes for TRYPTOPHAN SYNTHESIS are NOT EXPRESSED
define EPIGENETIC CONTROL
the STUDY of CHANGES in the REGULATION of GENE ACTIVITY and EXPRESSION that are NOT DEPENDENT on GENE SEQUENCE
- CHEMICAL MODIFICATIONS to DNA
define POST TRANSCRIPTIONAL CONTROL
a type of REGULATORY MECHANISM that STOPS PROTEIN SYNTHESIS after TRANSCRIPTION has OCCURRED
- occurs mainly within EUKARYOTES
- has SMALL SINGLE STRANDED RNA known as MICRO RNA (mina) (has around 22 NUCLEOTIDES
- binds to COMPLIMENTARY mRNA–forming actual DOUBLE STRANDED RNA and DESTROYS IT!!!!!!
- occurs during the DEVELOPMENT and accounts for CELL-TO-CELL DIFFERENTATION
BACTERIA:
has also SIMILAR SHORT RNAS within BACTERIAL CELL to cope with ENVIRONMENTAL STRESS
