unit 1 test- dna, rna Flashcards
What does DNA stand for?
Deoxyribonucleic acid
What are the building blocks (monomers) of DNA?
Nucleotides
What are the 3 parts of a nucleotide?
5-carbon sugar deoxyribose, phosphate groups, and nitrogenous bases
What are the 4 nitrogen bases present in DNA?
Adenine, thymine, cytosine, and guanine
What are purines? How many rings do they have?
Adenine and guanine, 2 rings
What are pyrimidines? How many rings do they have?
Thymine and cytosine, 1 ring
The double helix structure of DNA was discovered by 4 scientists - what are their names and what was the year?
Crick, Watson, Franklin, and Wilkins, 1953
What did Erwin Chargaff discover?
The ratios of adenine to thymine and guanine to cytosine are equal
What is the “backbone” of DNA made up of?
Deoxyribose and phosphate groups
What holds the DNA molecule together?
Hydrogen bonds
The nitrogen bases are always connected to the (sugar or phosphate)?
Deoxyribose (sugar)
What is a complementary strand?
The RNA strand that has the opposite (complementary) codons to the DNA strand.
What enzyme “unzips” the 2 strands of DNA in DNA replication?
DNA helicase
What does DNA polymerase do?
Forms new copies of DNA
If one strand of DNA is ATT CCG, what is the other complementary strand of DNA?
TAA GGC
What is mRNA?
messenger RNA carries protein info from the nucleus to the cytoplasm
What is tRNA?
transfer RNA transports amino acids to the ribosomes
What is rRNA?
ribosomal rna, combine with proteins and enzymes in the cytoplasm to form ribosomes
what are the 3 types of RNA?
mRNA, tRNA, and rRNA
What are 4 differences between RNA and DNA?
DNA has a double helix, has thymine, has deoxyribose, and replicates and stores information. RNA has a single helix, has uracil, has ribose, and converts genetic information to a format used to build proteins.
What is transcription? Where does it occur in the cell (nucleus or cytoplasm)?
DNA into RNA, occurs in the nucleus
Briefly describe the steps of transcription.
- RNA polymerase attaches to the promoter site
- DNA strand separates
- Adds RNA nucleotides to the DNA template
- RNA polymerase travels along the template strand
What enzyme is responsible for transcription?
RNA polymerase
How does mRNA move from the nucleus to the cytoplasm of a cell?
through nuclear pores
If an RNA molecule contains the sequence AAC GCU, what is the sequence of the DNA molecules from which it was made?
TTG CGA
What are introns
a segment of DNA or RNA that does not code for proteins and interrupts the sequence of genes
what are exons
a segment of a DNA or RNA containing information coding for a protein or peptide sequence
A series of 3 mRNA nitrogen bases that contains the information needed to make proteins are called what?
codon
What is the universal start codon and what amino acid does it code for?
AUG methionine
What are the 3 stop codons?
UAG UAA UGA
What is translation? Where does it occur in the cell (nucleus or cytoplasm)?
Protein synthesis, takes place in the cytoplasm
What does the word “mutation” mean?
Change of the structure of DNA
Mutations that produce changes in a single gene are called ____
Gene mutations/point mutations
Mutations that produce changes in whole chromosomes are known as _____
Chromosomal mutations
In what way(s), if any, do most mutations change organisms?
By changing its physical characteristics
What are the 3 examples of gene (point) mutations?
Base substitutions, deletions, and insertions
Insertions and deletions usually result in frameshift mutations. What does this mean?
the insertion or deletion of nucleotide bases in numbers that are not multiples of three
What are the 4 examples of chromosomal mutations?
deletion, duplication, inversion, translocation
What is a deletion mutation?
loss of one or more nucleotides
what is a duplication mutation?
one or more copies of a DNA segment is produced
what is an inversion mutation?
segment of the chromosome breaks off and reattaches in the reverse direction
what is a translocation mutation?
unusual rearrangement of chromosomes
