DNA Flashcards
What is the structure of a DNA nucleotide?
Pentose sugar (5 carbons)- deoxyribose
Nitrogenous base
Phosphate group
What 4 bases can the nitrogenous bases be?
Adenine, thymine, cytosine and guanine
How are the 3 components of the nucleotide joined together?
By a condensation reaction
What is the function of DNA?
Hold/store and pass genetic information from cell to cell and generation to generation
What does DNA contain?
The instructions for the growth and development of all organisms
Where does the condensation reaction take place?
Between the deoxyribose sugar and the phosphate group of another nucleotide
What bond is formed during a condensation reaction?
Phosphodiester bond- makes a dinucleotide
How is the sugar phosphate backbone created?
The chain of alternating phosphate groups and pentose sugars produced as a result of many phosphodiester bonds
Which bases are purine and which are pyrimidines?
Adenine and guanine- purine
Cytosine and thymine- pyrimidines
What does purine mean?
A double ring structure
What does pyrimidines mean?
A single ring structure
How do the bases on the 2 strands of DNA attach to each other?
Hydrogen bonding
What are the 2 polynucleotide strands like?
Running in opposite directions (anti-parallel)
How does a double helix form?
The uprights of phosphate and deoxyribose wind around one another to form a double helix
What is similar in both DNA and RNA?
Both types of nucleic acid
Both found in all living cells
Both needed to build proteins
Function of RNA?
Transfer the genetic code found in DNA out of the nucleus and carry it to the ribosomes in the cytoplasm
What is RNA the copy for?
For making protein or having a specific function e.g. carrying amino acids
What are the 3 types of RNA?
mRNA
rRNA
tRNA
What is mRNA’s role?
Copy used in translation
What is the role of rRNA?
Combined with proteins to form ribosomes
What is the role of tRNA?
Anticodon to pair with codon on mRNA- carries the specific amino acid
What are the components of a RNA nucleotide?
Phosphate group
Ribose sugar with a OH- group at the 2’ position
Nitrogenous base (A,C,G,U)
What does the OH group positioned at the 2’ make the RNA molecule?
Makes RNA more susceptible to hydrolysis- why DNA is the storage molecule and the RNA is the transport molecule with the shorter molecular lifespan
What sugar is in RNA?
Ribose
4 differences between RNA and DNA structure?
RNA- contains uracil, DNA-contains thymine
RNA- contains ribose pentose sugar, DNA- contains deoxyribose pentose sugar
RNA- single stranded, DNA- double stranded
RNA- shorter, DNA- longer
Structure of RNA in relation to its function?
Single stranded- easily binds to other molecules e.g. for translation
Shorter- only provides the code for one protein
Where is DNA found in eukaryotic cells?
In the nucleus- in the form of chromosomes
In eukaryotic cells, is DNA membrane bound?
Yes
Are there plasmids in eukaryotic cells?
No plasmids
Is DNA linear or non-linear in eukaryotic cells?
DNA is linear
Are DNA molecules longer or shorter in eukaryotic cells?
Longer
How are chromosomes formed?
DNA molecules occur in association with proteins called histones to form chromosomes
Is there DNA in chloroplasts?
Yes- there is circular DNA in the stroma
Is there DNA in the mitochondria?
Yes- circular DNA in the matrix
What is DNA like in prokaryotic cells?
DNA may be in the form of circular strands (plasmids)- can have variable number of plasmids
Is DNA membrane bound in prokaryotic cells?
No membrane bound
Is DNA shorter or longer in prokaryotic cells?
DNA molecules are shorter- form a circle
Where are circular chromosomes found in prokaryotic cells?
In the nucleoid region
