1.5.1 structure of DNA and RNA Flashcards
DNA defintion
Is a double helix with 2 polynucleotide chains held together by HB between specific complementary base pairs
What is the function of DNA?
holds genetic information.
What is the function of RNA?
RNA transfers genetic information from DNA to the ribosomes.
Ribosomes are formed from
RNA and proteins
Nucleotide is the monomer.
What is the polymer?
Nucleic acids (DNA or RNA)
What is DNA and RNA a polymer of
nucleotides
What is a DNA nucleotide made up of?
- a deoxyribose sugar
- a phosphate group
- a nitrogenous base
What are the 4 bases of DNA?
Adenine + Thymine and Guanine + Cytosine
What is an RNA nucleotide made up of?
- a ribose sugar
- a phosphate group
- a nitrogenous base
What are the 4 bases of RNA?
Adenine + Uracil and Cytosine + Guanine
What bonds join together each nucleotide?
phosphodiester bonds
What are the 2 strands of DNA joined together by?
hydrogen bonds between complementary base pairs
What is the sugar-phosphate backbone?
The chain of alternating phosphate groups and pentose sugars, produced as a result of many phosphodiester bonds.
what are the three types of RNA
mRNA and tRNA and rRNA
What is the difference between DNA molecules and RNA molecules? (2)
DNA molecules are double stranded but RNA molecules are single stranded
DNA is longer than RNA
What makes DNA compact?
double helix structure
what protects the base pairs
sugar phosphate backbone
What reaction joins DNa and RNA necleotides together and what bond is formed
condensation reaction and a phosphodiester bond
Why is there a very large variability/range of genes that DNA can code for?
sequence of bases has (almost) infinite variability
Why can DNA carry a lot of code?
it is an extremely large molecule
Structure of DNA
Base sequence
allows info to be stored
codes for amino acids and proteins
Double helix
compact
Long and large
can store lots of info
Hydrogen bonds
Easily broken between bases
enables DNA replication to occur
Sugar phosphate backbone
Strength and flexibility
DOuble stranded
enables semi conservative Replication to occur
If 20% of the bases in a DNA molecule are adenine, what percentages do the other bases hold?
Thymine = 20%
Guanine = 30%
Cytosine = 30%
How many hydrogen bonds are formed in a C-G pairing?
3
How many hydrogen bonds are formed in an A-T pairing?
2
Suggest how PNA (binds to DNA) affects the transcription of the section of DNA
PNA is complementary to DNA
PNA forms base pairs with DNA
Preventing/ reducing RNA polymerase activity/ bonding
Reducing/ stopping transcription
What group is attached to the 3’ carbon in a DNA nucleotide?
hydroxy
What group is attached to the 5’ carbon in a DNA nucleotide?
phosphate
How does DNA replicate
via semi - coservative Replication
Describe the structure of DNA and structure of a chromosomes
- polymers of nucleotides
- nucleotides consist of deoxyribose phosphate and organic nitrfogneous base
- Phosphodiester bonds between nucleotides
- DNA double helix held by H bonds
- 2 strands held by hydrogen bonds
- adenine, thymine, cyotsine and guanine
- DNA is associated with histones/ proteins
- During mitosis/ when visible chromsomeoes cons tis of two chromatids joined at a centromere
Describe the structure of DNA (5)
- polymer of nucleotides
- each nucleotide is formed from deoxyribose, a phosphate group and an nitrogenous base
- phosphodiester bonds
- double helix held together by hydrogen bonds
- H bonds between: adenine + thymine, and also cytosine + guanine
Describe how a phosphodiester bond is formed between two nucleotides within a DNA molecule. (2)
- Condensation reaction
- between phosphate and deoxyribose
- catalysed by DNA polymerase
