Unit 8 Flashcards
Nucleic acids are
polymers of nucleotides
has its own unique sequence of bases known as its primary structure.
nucleic acids
what makes up nucleic acids primary structure
bases
They are large molecules in the cell nucleus storing information and direct activities for cellular growth and reproduction
nucleotides
A nucleotide is composed of a
base, a sugar, and a phosphate group
(bond between PO4 and sugar)
phosphodiester linkages
When nucleotides are joined by phosphodiester linkages, (bond between PO4 and sugar)
polynucleotides are formed
2 most important nucleic acids are
DNA (deoxyribonucleic acid) & RNA (ribonucleic acid).
Is DNA or RNA larger
DNA
is the inherited genetic material controlling protein synthesis.
DNA
DNA structure
It is a double helical structure, where the helix is made up of sugar-phosphate groups.
The double helix consisted of
2 polynucleotide strands winding about each other like a spiral staircase.
are seen within the structure which are H bonds between bases
Bridges
The H bond formed is between
the bases, adenine & thymine (2 H bonds) and guanine & cytosine
(3 H bonds) The pairs AT and GC are called
complimentary base pairs
Bases used in DNA are both
purine (adenine & guanine) and pyrimidine (cytosine & thymine)
Sugar used in DNA is a
pentose, deoxyribose.
RNA Structure
The structure is with single chain instead of a double helix as in DNA.
The sugar used in RNA is another
pentose, ribose.
RNA The base pairs are
adenine & uracil and guanine & cytosine.
Alterations in the DNA base sequence leads to
gene mutation.
Small living particles, with 3 to 200 genes, that cannot replicate without a host cell are called
Viruses.
DNA replication takes place in the
nucleus
begins with the “unzipping” of the parent molecule as the H bonds between the base pairs are broken.
DNA replication
Replication takes place from
5 primer (5’) to 3 primer
(3’) Helicase is
the enzyme that splits the two strands.
When a cell divides, each of its double strands of DNA
DNA splits into two single strands
The enzyme, primase produces
short complementary RNA fragments called primers
DNA polymerase
catalyze the replication at open DNA sections termed, replication forks.
what are DNA polymerase
an enzyme
Each of these single strands acts as a template for a new strand of complementary DNA
replication forks
Leading strand
one of the new strand is synthesized continuously and lagging strand is synthesized discontinuously in short, separate segments called Okazaki fragments.
DNA ligase
connects the Okazaki fragments by phosphodiester linkages, leading to the formation of a new lagging strand which matches the leading DNA strand.
end product of DNA replication
2 identical copies of DNA
There are 3 major types of RNA in the cells
mRNA, rRNA and tRNA.
• Messenger RNA (mRNA)
carries genetic information from DNA to ribosomes. DNA is situated within the nucleus while ribosomes appear outside the nucleus.
• Ribosomal RNA (rRNA)
when combined with proteins yield ribosomes, which is the protein synthesis site. It is the most abundant type of RNA.
• Transfer RNA (tRNA)
get specific amino acids to the ribosome for protein synthesis. This RNA interprets the genetic information in mRNA into the amino acid sequence. Each tRNA contains an anticodon, which is a series of 3 bases that complements 3 bases on mRNA. Codon is the set of 3 nitrogen bases representing an amino acid.
Transcription takes place in the
nucleus and then moves onto the cytoplasm
It is the process by which DNA is copied to mRNA, which carries the information needed for protein synthesis.
transcription
Partial unwinding of the double helix must occur before _______ can take place
transcription
Partial unwinding of the double helix is catalyzed by the
enzyme, RNA polymerase
how many strands are transcribed in transcription, while both strands of DNA are copied in replication.
one
Transcription takes place in how many steps
two
end product of transcription
strand of mRNA
DNA template strand —–>
pre-messenger RNA —-> mature RNA
The process takes place within the cytoplasm
DNA translation
how many steps in translation
. It involves 3 steps- initiation, chain elongation and termination. tRNA molecules convert the information in mRNA into amino acids by a process called translation. mRNA binds to ribosomes and each tRNA gets attached to specific amino acids according to their anticodons
Protein synthesis starts when
mRNA binds to a ribosome.