Overview of Genome Transmission and Expression Flashcards
What is DNA known for?
information
What is RNA known for?
decoding
What is protein known for?
work
What genetic information do cells have?
DNA and RNA
What genetic information do viruses have?
RNA
At what length does replication occur?
the entire DNA sequence
At what length does transcription occur?
snippet of DNA sequence
What is the flow of genetic information?
unidirectional
What is the function of DNA?
physically stores genetic information in a stable, heritable form
What four nucleotides make up DNA?
guanine, adenosine. thymidine, cytosine
What carries the information “code”?
the linear sequence of nucleotides in DNA
What are the base pairs in a double helix?
A pairs with T and C pairs with G
What is the direction of each strand of DNA?
directional or asymmetric - the two strands are anti-parallel to each other
How is DNA replicated for transmission?
- original strands are separated
- new DNA strands are synthesized in an anti-parallel manner by DNA polymerase using the old strands as templates
- nucleotides are added in a complementary manner
- two identical double-stranded DNA molecules from one original molecule
- all cellular sequences in an organism comprise its genome
How is one single strand DNA a backup?
a single strand can act as a template for a double strand
What helps chromosomes to segregate accurately?
copied chromosomes are held together prior to separation
What is the transmission of the genome?
- replication: accurate copying of information
- segregation: correct separation of copies
- transfer of copies into new cells created by division of the original cell
What follows each step of cell division?
safety net and checkpoints
What must be expressed before genetic information is stored in the genome?
transcription
What is transcription?
copying of a segment of DNA into RNA
What happens after transcription?
RNA is either used directly by the cell or used as an information template to direct synthesis of a particular protein (translation)
What is special about RNA?
can act as a storage molecule and synthesize proteins on its own (catalysis; w/o protein)
How does RNA polymerase work?
uses one strand of DNA as a template to synthesize a complementary RNA strand
What is the difference between RNA and DNA?
RNA contains uracil instead of thymine
What initiates transcription?
specific DNA sequences instruct RNA polymerase where to start and to stop transcribing
What is the primary transcript?
the RNA produced immediately after transcription, which is processed into the final RNA product
What are the three types of RNAs?
- mRNA
- tRNA
- rRNA
What is the function of mRNA?
carries the sequence encoding a protein and acts as the template for translation
What is the function of tRNA?
acts as an adapter that “reads” the mRNA and brings the encoded amino acids for protein synthesis
How long are tRNAs?
80-100 nucleotides in length
What is the function of rRNA?
together with ~100 proteins form ribosomes, which are protein synthesis factories where translation occurs
How are nucleotides read?
3 nucleotides/ protein
What is translated into proteins?
mRNA
How do proteins have potential for variation in structure and function?
proteins are synthesized from 20 different amino acids
What is function of proteins?
carry out most cellular function (e.g. structural and catalytic)
What are the characteristics of proteins?
- can range from a few amino acids long (e.g. calmodulin) to many thousands (e.g. hemagglutinin)-typically between 100-1000 amino acids in lengths
- may contain distinct separate proteins that come together to form a functional unit (e.g. hemagglutinin)
What translations the mRNA?
tRNA and rRNA
What is translation?
turns the information from an mRNA into a protein
What is a codon?
triplets of nucleotides in the mRNA that encode each amino acid
What initiates and terminates translation?
distinct sequences in the mRNA
What order does tRNA decode?
recognizes each codon in order from 5’ to 3’
Where does translation occur?
translation is performed by the ribosome, which is composed of rRNAs and proteins
What is the cellular structure of prokaryotes?
do not have internal membrane-bound compartments (e.g. the nucleus)
Where is DNA located in prokaryotes?
in the nucleoid
T or F: transcription and translation can occur simultaneously in prokaryotes
true
What is cellular structure of eukaryotes?
contain several membrane-bound organelles (e.g. the nucleus, mitochondria, chloroplasts)
Where is DNA located eukaryotes?
in the nucleus
Where does replication and transcription occur in eukaryotes?
in the nucleus
Where does translation occur in eukaryotes?
translation occurs in the cytoplasm within ribosomes so mRNA must be exported to cytoplasm for translation
T or F: transcription and translation can occur simultaneously in eukaryotes?
false
