Mr P bio 7 Nucleic Acids Flashcards
what are the 3 components of a nucleotide?
phosphate group, organic base and pentose sugar
what does DNA stand for?
Deoxyribonucleic acid
what is the monomer of DNA?
nucleotide
what are the 3 components of DNA?
phosphate group, organic base and deoxyribose sugar
what is the structure of DNA?
double helix consisting of 2 polynucleotide strands held together by hydrogen bonds between the paired bases
which bases pair with which in DNA?
Adenine with thymine
guanine with cytosine
how many hydrogen bonds does each base pair form?
A-T= 2
G-C=3
what are the two bonds found within DNA?
hydrogen and phophodiester
where are phosphodiester bonds found?
between the sugar and phosphate group
how are DNA strands formatted?
they are antiparallel
how is DNA adapted for its function as a storage molecule? (6)
-DNA has a sugar-phosphate backbone
-DNA is a really large molecule so can store lots of info
-DNA is coiled into a helix so is compact
-base sequence codes for amino acids/ proteins
-DNA is double stranded (covered later on in year)
-DNA has many weak H bonds for replication
why is DNA’s sugar phosphate backbone an adaptation for its function as a storage molecule?
when coiled into a double helix, this provides strength and stability and protects the bases from damage
What are the 3 components of RNA?
Phosphate group, nitrogenous base, ribose sugar
What are the 3 types of RNA?
Messenger, transfer and ribosomal
What are the differences between DNA and RNA?
RNA-single stranded, uses uracil, 1 polynucleotide chain, uses ribose sugar, several 100s-1000s of nucleotides in a chain
DNA-double stranded, uses thymine, 2 polynucleotide chains, uses deoxyribose’s sugars, many millions of nucleotides in a chain
What is the structure of mRNA?
Single stranded polynucleotide chain that is a copy of a single gene on the DNA so length depends on no of bases in gene so shorter than DNA
WhT does mRNA have instead of thymine?
Uracil
how is the structure mRNA related to the structure DNA?
it is complementary
what is the sequence of 3 bases called?
codon
how many amino acids does each codon code for?
one
approximately, how many nucleotides are contained in tRNA’s polynucleotide chain?
75
how many polynucleotide chains does tRNA contain?
1
what is the structure of tRNA compared to?
clover leaf
what are the different components of tRNA?
amino acid attachment site, sugar phosphate backbone, anticodon
within tRNA, what bonds join the complementary bases?
hydrogen
what is the role tRNA?
to carry a specific amino acid to the site of protein synthesis and its anticodon base-pairs with the codon on the mRNA molecule
what are the differences between DNA and tRNA?
DNA-deoxyribose, thyomine, 2 polynucleotide strands, many millions of nucleotides in chain
tRNA- ribose, Uracil, 1 polynucleotide strand, about 75 nucleotides in a chain
what are the components of ATP?
nitrogenous organic base and 3 phosphate groups
what is ATP formed from?
from ADP and inorganic phosphate
what reaction occurs to form ATP and what bond is formed?
condensation reaction and requires lots of energy to add a phosphate group to ADP so a high energy covalent bonds is created
what enzyme formed ATP?
ATP synthase
what happens when ATP is hydrolysed?
easily broken down back into ADP and inorganic phosphate and when this happens the bond between the 2nd and 3rd phosphate breaks and releases large amounts of usable energy
why is ATP useful?
- energy released in small amounts
- ATP is soluble
- involves a single reaction
what are 3 uses of ATP?
active transport, muscle contraction and protein synthesis
which enzyme speeds up the hydrolysis of ATP?
ATP hydrolase
what is a gene?
a section of DNA that codes for a particular polypeptide and can also code for a functional RNA
what is the location of a gene on a particular DNA molecule called?
locus
what is the genome?
all of an organisms genes
what is the name for the range of proteins that a cell produces using its DNA?
proteome
what is an allele?
different forms of the same gene
why is the genetic code described as being universal?
triplet codes code for the same amino acids in all organisms
why is the genetic code described as being non- overlapping?
the ribosome reads each base only only once in the codons
why is the genetic code described as being degenerate?
more than one triplet codes for an amino acid
how does a change in the base sequence of DNA lead to an enzyme not functioning? (4)
-DNA base sequence codes for sequence of amino acids/ primary structure
-changing the H, ionic and disulphide bonds between R groups
-change in tertiary structure and shape of active site
-substrate unable to bind so no enzyme- substrate complexes formed
how is the DNA in a prokaryotic cell different to in a eukaryotic cell?
prokaryotes contain a single circular DNA molecule and often contain one or more plasmids whereas eukaryotic cells contain chromosomes
what is a chromosome?
linear DNA molecule wrapped around a protein called a histone to form a rod like structure
where is non-coding DNA found?
in between genes
what is a non-coding repeat?
a sequence of bases which is repeated a number of times
what is non-coding DNA within a gene called?
intron
list the 5 differences between prokaryotic and eukaryotic DNA
prokaryotic- stored in one long, circular DNA ring, smaller, no associated proteins, doesn’t form chromosomes, no non- coding DNA in plasmid
eukaryotic- linear DNA, larger, associated with proteins called histones, forms chromosomes, contains introns and non-coding repeats
give 2 ways in which the hydrolysis of ATP is used in cells
processes such as active transport
to add phosphate to other substances and make them more reactive
describe how ATP is resynthesised in cells
ATP synthase is used to change ATP and phosphate to ATP during respiration/ photosynthesis
explain how the organic bases help to stabilise the structure of DNA
hydrogen bonds between base pairs holds 2 strands together and many hydrogen bonds provide strength
explain how humans and grasshoppers can have a similar percentage of each base in their DNA
they have different genes so triplets are in a different order so different amino acid sequence coded for
Give three ways in which the DNA in a chloroplast is different from DNA in the nucleus.
In Chloroplasts:
-DNA shorter
-fewer genes
-circular
-not associated with proteins
-introns absent
