unit 6 Flashcards
what is DNA?
genetic code for traits
DNA is made of long chains of…
nucleotides
what are the three parts of a nucleotide?
-sugar
-phosphate
-nitrogenous base
what are the 4 nitrogen bases (DNA)
-adenine
-thymine
-cytosine
-guanine
what is a codon? what do they code for?
3 nitrogenous bases on mRNA coding for an amino acid
explain the process of DNA replication
the unwinding of the double helix and separation of the DNA strands, the priming of the template strand, and the assembly of the new DNA segment
helicase
the unzipping enzyme, breaks the hydrogen bonds between bases
DNA polymerase
the builder, replicates DNA molecules
primase
the initializer, makes the primer (made of RNA) that indicates where DNA polymerase should begin
ligase
the gluer, glues DNA fragments together
okazaki fragments
short sections of DNA formed at the time of discontinuous synthesis of the lagging strand during replication of DNA
why is DNA replication considered to be “semi-conservative”?
when a DNA molecule replicates, each new double helix consists of one strand from the original DNA molecule and one newly synthesized strand, essentially “conserving” half of the original DNA molecule in each new copy
replication fork
a Y-shaped region where the parent DNA double helix splits into two strands, subsequently copied
leading strand
the strand that runs in the 5’ to 3’ direction towards the replication fork
lagging strand
the strand that runs in the 5’ to 3’ direction away from the replication fork
base pairs
two complementary nitrogenous bases that bond together to form the rungs of DNA’s double helix
5’ to 3’
the direction in which new DNA is synthesized
sugar in DNA and RNA
DNA: deoxyribose
RNA: ribose
bases in DNA and RNA
DNA: adenine, thymine, cytosine, and guanine
RNA: adenine, uracil, cytosine, and guanine
number of strands in DNA and RNA
DNA: 2
RNA: 1
purpose of DNA and RNA
DNA: contains hereditary information
RNA: helps make protein
mRNA
this RNA brings the information from the DNA about what the order of amino acids will be
tRNA
this RNA collects amino acids and transfers them to the ribosome
rRNA
this RNA makes up the parts of the ribosome that help build the proteins
where in the cell does transcription take place?
nucleus
where in the cell does translation take place?
ribosome
what types of RNA are involved in transcription?
mRNA
what types of RNA are involved in translation?
mRNA and tRNA
what is the purpose of transcription?
make mRNA
what is the purpose of translation?
make a protein
the creation of mRNA, or mRNA synthesis, occurs during…
transcription
the creation of proteins, or protein synthesis, occurs during…
translation
what is a mutation?
permanent change in nucleotide/DNA sequence
what can cause a mutation?
errors during DNA replication during cell division, exposure to environmental factors like radiation, smoking or certain chemicals, viral infections, or even spontaneous occurrences within the cell itself
frameshift mutation
if there’s an addition (insertion) or deletion of extra nucleotides of DNA
point mutation
if a single nucleotide is changed or substituted
silent point mutation
when the new codon codes for the same amino acid
missense point mutation
conservative missense: the new codon codes for a different amino acid that works similar to the original amino acid
non conservative missense: the new codon codes from a different amino acid that works differently from the original amino acid
nonsense point mutation
when the new codon codes for a stop codon
insertion mutation
when an additional base is added to the nucleotide sequence
deletion mutation
when a base is removed from the nucleotide sequence
what does epigenetics do to our DNA?
epigenetics is when environmental factors influence which genes are expressed. methyl groups attach the DNA causing it to wrap around histones more tightly, making it so those genes cannot be read or expressed. this process is called methylation. these methyl tags can be passed on through generations.
mutagen
in genetics, a mutagen is a physical or chemical agent that permanently changes genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level
