S5 - Unit One Flashcards
What is the basic subunit of any nucleic acid?
A nucleotide
What is the structure of DNA nucleotides
How is the structure of a sugar phosphate backbone composed?
A chemical bond forms between the phosphate group of one nucleotide and the 3’ end of the sugar on another
What is the structure of a sugar phosphate backbone?
What holds bases together?
Weak hydrogen bonds
What are prokaryote cells?
Cells containing a single circular chromosome and smaller plasmids
What are eukaryote cells?
Cells containing linear chromosomes in their nucleus
What are examples of prokaryotes?
Bacterial
What are examples of eukaryotes?
Plants, animal, yeast
How are eukaryote chromosomes organised?
Tightly coiled and packaged around histones
Eukaryotes contain linear chromosomes in their mitochondria and chloroplasts - T or F
False
Eukaryotes contain circular chromosomes in their mitochondria and chloroplasts - T or F
True
What is the exception to eukaryote cells and why?
Yeast cells, they also contain circular plasmids
What is gel electrophoresis?
A technique which separates DNA molecules by subjecting them to an electrical current
Why is DNA replicated and when does this take place?
- To ensure all the daughter cells have the same genetic info as the parent cells amd to maintain the chromosome diploid compliment
- Before mitosis
What is a primer and its role in DNA replication?
A short strand of nucleotides which bind to the 3’ end of the template DNA strand allowing DNA polymerase to add free DNA nucleotides
What is the first stage of DNA replication?
DNA is unwound and H bonds between bases are broken to form 2 template strands
What is the second stage of DNA replication?
DNA polymerase adds free DNA nucleotides using complimentary base pairing to the deoxyribose 3’ end of the new DNA strand which is forming
How do the leading strand and lagging strand differ?
Leading - replicated continuously
Lagging - replicated in fragments
Why is the lagging DNA strand replicated in fragments?
Because DNA polymerase can only replicate in the 3’ to 5’ end
What enzyme is used in the lagging strand that isn’t in the leading strand during DNA replication and what does it do?
Ligase, joins the DNA fragments
Why is a template DNA strand needed in DNA replication?
Provides a template for the genetic code
Why is a supply of DNA nucleotides needed in DNA replication?
To produce the new strand of DNA
Why is a supply of energy needed in DNA replication?
To provide DNA polymerase with energy
Why is a DNA polymerase needed in DNA replication?
To join the complementary free DNA nucleotides to the 3’ end
Why is a primer needed in DNA replication?
To all the attachment of DNA polymerase to start replication
What is a polymerase chain reaction (PCR)?
A reaction that creates many copies of DNA outside the body
What are some uses of PCR?
- Help to solve crimes
- Settle paternity suits
- Diagnose genetic disorders
What is the temp. required for the first stage of PCR and what happens?
92-98 oC
Strands separate
What is the temp. required for the second stage of PCR and what happens?
50-65 oC
Primers bind to specific target sequence
What is the temp. required for the third stage of PCR and what happens?
70-80 oC
The heat tolerant DNA polymerase replicates the region of DNA
What are the differences between DNA and RNA?
DNA: double stranded, A-T, deoxyribose
RNA: single stranded, A-U, ribose
What are the three types of RNA?
tRNA (transfer)
mRNA (messenger)
rRNA (ribosomal)
What do each of the RNA types do?
t - carries its specific amino acids to the ribosome
m - carries a complimentary copy of DNA from the nucleus to the ribosome
r - forms the organelle: ribosome
What are the two processes involved in protein synthesis?
Transcription & Translation
What is a codon and what do they do?
A triplet of bases on a mRNA molecule
Code for a specific amino acid
Where is mRNA transcribed?
From DNA in the nucleus
Where is mRNA translated and what does it produce?
Ribosomes in the cytoplasm
Proteins
What is transcription?
The synthesis of mRNA from a section of DNA
What is the fist transcript produced called in transcription?
The primary transcript
What is the second transcript produced called in transcription?
The mature transcript
What process makes the mature transcript in transcription?
RNA splicing