Expression of Genes Flashcards
Name 3 types of common proteins used in the body
- Antibodies
- Enzymes
- Hormones
bind to foreign particles (like viruses and bacteria) to help protect the body against invaders
Antibodies
facilitate chemical reactions in cells and help form new DNA molecules by reading and modifying the genetic information in DNA
Enzymes
facilitate long-range communication between tissues, cells, and organs
Hormones
a tightly controlled process by which the information stored in DNA is converted into instructions for making proteins
Gene Expression
What are the 2 stages of gene expression?
- Transcription
- Translation
the phase of gene expression when an organism’s DNA is converted to RNA
Transcription
Where does transcription vs translation occur in eukaryotic cells?
Transcription - Nucleus
Translation - Cytoplasm
states that DNA is first transcribed to make a new RNA molecule with complementary bases, then the RNA code is deciphered at the ribosome to create the correct sequence of amino acids to make proteins
Central Dogma
DNA encodes RNA and RNA encodes proteins
Central Dogma
the phase of gene expression in which cellular machinery reads each RNA codon and adds the corresponding amino acids together to produce polypeptides
Translation
the phase of gene expression in which the transcribed RNA sequence is used to make proteins
Translation
Occurs when the DNA is opened by helicase, then RNA polymerase uses RNA nucleotides to copy the DNA sequences
Transcription
the building blocks of proteins
Amino Acids
Coded for by a sequence of 3 base pairs next to each other
Amino Acid
How many possible codons are there? How many amino acids do they code for?
The 64 codons possible code for 20 different amino acids and the termination of the polypeptide chain
these are the code to determine which amino acids need to be bonded to each other to provide the proper shape and functionality of the protein
Base Pairs
What happens once translation is complete?
the polypeptide will fold into its correct structure > then may need to be further processed, moved to a specific location, or added to other polypeptides before it begins its function as a protein in the cell
the molecules in cells that carry codes from the DNA in the nucleus to the ribosomes in the cytoplasm
mRNA
What type of RNA is made during transcription?
mRNA
the enzyme that adds the appropriate RNA nitrogenous base pairs to the template strand of DNA
RNA Polymerase
a 3 letter sequence of DNA or RNA that contains information
Codon
codons that contain the instructions for specific amino acids
RNA Codons
chains of amino acids
Polypeptides
What is the role of mRNA in gene expression?
To carry information from DNA to the ribosome to enable protein synthesis
What is mRNA produced from?
The antisense DNA strand
What is the antisense DNA strand?
The antiparallel strand that runs in the 3’ to 5’ direction
Describe the life cycle of mRNA
Short - it’s degraded after translation
What 3 things make up the structure of mature mRNA?
- Start codon
- Coding sequence
- Stop codon
is read from the 5’ end and gives instructions to the ribosome to start assembling amino acids as laid out in the RNA sequence
Start Codon
is located at the 3’ end of the coding sequence and tells the ribosome to stop assembling amino acids
Stop Codon
What does directionality of DNA and RNA mean?
the ends of each strand are not identical and are distinct from each other
What dictates the directionality of DNA and RNA?
the sugar-phosphate backbone
Why is directionality important in DNA and RNA?
Ensures transcription and translation occur in a uniform manner
What would occur without DNA and RNA directionality?
- DNA and RNA machinery could read nucleotides in either direction
- Could then generate sequences with entirely different meanings
- Would then result in different proteins made of different amino acids
Why is only 1 strand of DNA the coding strand?
Directionality to avoid cell machinery reading nucleotides in the wrong direction
What 4 molecules are involved in translation?
- mRNA
- tRNA
- rRNA
- A ribosome
the molecules that brings the appropriate amino acids from the cytoplasm to the correct position in the polypeptide chain during translation
tRNA
Serves as the physical link between the mRNA sequence and the individual amino acids
tRNA
the part of the ribosome that assembles the amino acids according to the code that the mRNA has brought from the DNA
rRNA
Interacts with a set of proteins to form the ribosome
rRNA
the site for protein synthesis within a cell
Ribosomes
Ribosomes contain 2 types of what? And what do they have?
Subunits: Large and Small
They each have their own special rRNA molecules
a mutation caused by the addition or deletion of a base pair or base pairs in the DNA of a gene resulting in the translation of the code in an unnatural reading frame from the position of the mutation to the end of the gene
Frameshift Mutation
Occur when start and stop locations for translation are poorly defined
Frameshift Mutation
When are frameshift mutations more likely to occur?
in a region of repeat sequence
What are 4 examples of frameshift mutations?
- Colorectal cancer
- Prostate cancer
- Ovarian cancer
- Breast cancer
