Nucleic acids Flashcards
What are nucleotides
nucleotides are monomers consisting of three molecules:
- a pentose sugar
- nitrogenous base
- phosphate group
What type of reaction forms a nucleotide
condensation reaction
What does DNA stand for
Deoxyribonucleic acid
What does RNA stand for
ribonucleic acid
Describe the structure of DNA
double helix made up of two polynucleotide strands
What type of bond is formed between bases
Hydrogen bonds
What is the relationship between the polynucleotide strands of one DNA molecule
- The polynucleotide strands are anti-parallel
- one strand runs from 3’ to 5’
- the other strand runs from 5’ to 3’
what does 3’ or 5’ mean
(3 prime or 5 prime)
5’ means carbon 5 is available for a phosphate to bind
3’ means carbon 3 is available for a phosphate to bind
where is DNA stored
nucleus
what structures are formed from DNA
chromosomes
what are the four bases (DNA)
GCAT
guanine, cytosine, adenine, thymine
What 5 elements make up DNA
Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus
what does Adenine pair with (DNA)
Thymine
what does Thymine pair with (DNA)
Adenine
what does cytosine pair with
Guanine
what does Guanine pair with
Cytosine
what does Adenine pair with (RNA)
Uracil
What are the four bases (RNA)
guanine, cytosine, adenine, Uracil
Why do the bases only pair with specific bases
they are complimentary in size and shape
What type of bond is between A and T
Hydrogen double bond
What type of bond is between G and C
Hydrogen triple bond
What type of bonds are between nucleotides
Phosphodiester bonds
What is a nucleotide made up of (DNA)
what shapes represents them
- Phosphate group (circle)
- Deoxyribose sugar (pentagon)
- Nitrogenous base (rectangle)
What is a nucleotide made up of (RNA)
what shapes represent them
- Phosphate group (circle)
- Ribose sugar (pentagon)
- Nitrogenous base (rectangle)
explain the condensed structures of DNA
Double helix - chromosome
- Double helix
- nucleosomes, double helix wraps around histone
- nucleosomes condense to form unwound chromatin
- unwound chromatin winds to form condensed chromatin
- condensed chromatin condenses more and forms a single chromosome
What are the 4 differences between RNA & DNA
- RNA is a single stranded poly nucleotide whereas DNA is double stranded
- Thymine is replaced by Uracil
RNA (GCAU) DNA (GCAT) - RNA is ribose sugar, DNA is deoxyribose sugar
- RNA has a much shorter strand than DNA
REMEMBER:
DNA can bind with RNA
DNA can bind with RNA
What stage does DNA replication occur at
Interphase
Describe the first stage of DNA replication
The DNA double helix is ready to be replicated. The DNA strand unwinds ONLY in the section that needs to be replicated
Describe the second stage of DNA replication
The enzyme DNA helicase causes the two strands of DNA to separate by breaking the hydrogen bonds between complimentary bases. DNA helicase runs from 3’ t 5’ as the active site is complimentary to 3’
Describe the third stage of DNA replication
Free floating nucleotides are attracted to their complimentary bases, hydrogen bonds between them form naturally. The enzyme DNA polymerase creates the phosphodiester bonds in the backbone (condensation reaction)
Describe the fourth stage of DNA replication
The two identical strands of DNA are formed. In each helix one strand is an original strand and one is a new strand.
what is the model for DNA replication called
semi-conservative replication
what is the structure of ATP
Adenine - a nitrogen containing base
Ribose
phosphates
what is ATP used in
metabolic processes movement active transport secretion activation of molecules
What causes water molecules to stick together
hydrogen bonds between the positive poles on one water molecule and the negative charges on another (as water is dipolar due to the pos charge on the hydrgoen and the neg charge on oxygen)
what is water needed for
- as a solvent, dissolves other substances
- metabolism, used to break down substances in hydrolysis
