1.2 - Language of Life Flashcards
How many chromosones do human body cells contain?
46
How are pictures of chromosones arranged in a karyotype?
In size order - largest to smallest.
These chromosones however are only visible during division
What happens once to photos of chromosones once they are arranged in size order?
They are numbered accordingly
For each pair of chromosones, do they come from the mum or the dad?
Both. Within a chromsone pair there is one maternal and one paternal chromosone.
Which pair of chromosones aren’tgiven a number in a karyotype?
Sex chromosones
What shape are the two female sex chromosones
Two x-shaped chromosones
What shape are the two male sex chromosones
One x shaped chromosone and one y shaped chromosone
What are the 44 non-sex chromosones know as
Autosomes
When does DNA replication occur
Prior to cell division
What is a good way to decsribe the nature of the replicated DNA after replication?
Two identical copies - one for each daughter cell
Why are new cells required to be made for the body
For growth and repair
Before duplication, how many DNA molecules does each chromosone have
1
Once DNA has been duplicated (before division), how many chromatids does a chromosone consist of
two, each cntaining a copy of the DNA molecules
What part of the chromosone are the two sister chromatids connected at before division
Centromere
What enzyme breaks hydrogen bonds connecting base pairs in DNA for replication
Helicase
What is the name for the two seperate strands of DNA once seperated for replication
Templates
What enzyme links complementary free nucleotides
Polymerase
What does the enzyme ligase do?
ensuring all sections of the DNA molecule have been sealed
What is the name of the process that ensures there is one old strand and new strand of DNA after replication
Semi-conservative replication
Why is there DNA polymerase and RNA polymerase?
DNA polymerase is used in the replication of DNA for division. It pairs complementary free DNA nucleotides with the original template to create a new strand. RNA polymerase is used in protein transcription to make small sections of RNA to act as mRNA and leave the nucleus. It will attach complementary free RNA nucleotides with an unraveled strand of DNA
What is the name of the section at which the DNA starts going it’s seperate ways when unravelling
DNA Fork
Can multiples polymerases synthesise at the same time?
Yes multiple polymerases can synthesise new strands of DNA a the same time using each unwound strand from the original double helix as a template
What are the names of the two different unwound DNA strands according to the direction they synthesise
Leading strand and Lagging strand
What is the nature of how the leading strand is synthesised
continuously
How is the lagging strand synthesised
In smaller segments which are joined together to make one continuous strand
What type of Polymer is a substance most likely if it ends in ‘ase’
An enzyme
How does Helicase ‘unzip’ the DNA
by breaking hydrogen bonds
What is the function of a primer?
Primase can’t figure out where to get started with the synethisis of new strands, hence it needs a primer to show it where
what are primers made from?
RNA
Are DNA strands parrallel or anti-parrallel
anti-parrallel
Where does the name 5 prime to 3 prime come from?
The sugar phosphate backbone, specifically the arrangement of the carbon in the sugar (typically in diagrams where the 5 carbon sugar is represented with a pentagon, which ever way the point of the hexagons are going is towards the 5, aka 5 prime to 3 prime
Which direction can DNA polymerase only build in
5 ‘ to 3’, hence it moves along the existing template in the 3’ to 5’ direction - always towards the 5
Why is one strand lagging?
Since polymerase can only build in 5’ to 3’ direction, it needs to keep returning to the start to continue building in sections
Does DNA polymerase often make mistakes
No - it has proof-reading abilities so is very rare
What is another name for the genetic code
The genome
Why does even a simple cell require many genes
Because all cell needs complex reactions to take place and for many different proteins to be made, hence it needs lot’s of different instructions
where does transcription occur
Inside the nucleus
What happens in transcription
A gene on the DNA (a section of DNA) is transcribed onto messenger RNA (mRNA).
Why is mRNA helpful
because DNA is too large to leave the nucleus so a message of the code is taken instead
What is the first step of transcription
DNA unzips (hydrogen bonds broken) exposing the bases of the gene that need to be coded
What is step 2 of transcription
Free RNA nucleotides (A, U, G, C) join to the gene bases on the template strand. RNA polymerase links to complementary nucleotides forming a messenger RNA molecule
What is step 3 of transcription
The mRNA molecule leaves the nucleus via a nuclear pore
What is step 4 of transcription
DNA zips back up, DNA is unaltered
Describe the structure of mRNA
The mRNA formed is made up of RNA bases found as triplets called a codon.
What does each codon code for?
A specific amino acid
Do codon tables refer to codons on the DNA, mRNA, or tRNA strand?
mRNA
Where does translation occur?
Cytoplasm
What is mRNA translated into during translation
Amino acid sequence which forms a polypeptide chain
What organelle does mRNA attach to for translation
Ribosome
What are ribosomes made of
rRNA and protein
Where is rRNA synethsisted?
Nucleolus
What are the 3 bases on tRNA known as
Anti-codon
What does each anti-codon correspond to
A specific amino acid
Where do tRNA anti-codons attach to during translation
Corresponding mRNA codon)
Describe the nature in which a ribosome translates mRNA
Feeds through the Ribosome, proccessing one amino acid at a time, like paper being fed through a ticker timer
How do amino acids attach to eachother in a peptide chain
Peptide link
Once the tRNA drops of the Amino acid to the polypeptide chain, can it pick up another amino acid?
Yes, excpet it must be specific to the anti-codon it possesses
What is the last amino acid on a sequence called and what does it do?
Stop Amino acid and signifies the completion of the polypeptide chain
What happens once all the mRNA has been read and proccessesed through the ribosome
The polypeptide chain moves away from the ribosome and fold into it’s protein shape
What are sections of the DNA which are expressed called?
exons
What are sequences called that are transcribed but then cut out of the mRNA before translation called?
Introns
What’s another name for introns within eukaryotic cells
non-coding sequences
What’s the name for RNA that has not had the introns spliced out
Immature mRNA
What’s the name for RNA once the introns have been splied out
Mature mRNA
