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year 1 - dentistry > nucleus, genes, dna > Flashcards

nucleus, genes, dna Flashcards

1
Q

what does the nucleus contain

A
  • contains the genetic material of the cell in the form of DNA - deoxyribonucleic acid
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2
Q

what are 4 structures of the nucleus

A
  • double phospholipid membrane
  • nuclear envelope which contains nuclear pore
  • nucleolus
  • membrane is continuous with other membranes that form the ER
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3
Q

what is the function of the nuclear pore and structure of nuclear pore

A
  • allows things into the nucleus - mainly proteins needed for DNA replication and transcription
  • allows things out such as RNA - requires atp
  • nuclear envelope contains nuclear pore
  • ring of protein and anchor protein which hold the rings of protein in the nuclear envelope
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4
Q

what is the nucleolus and its functions and what are ribosomes

A
  • nucleolus is where the ribosomes, required for protein synthesis are assembled
  • ribosomes are a mixture of rna and proteins
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5
Q

what does dna contain

A
  • dna contains all the information required to produce and maintain all the components of a cell
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6
Q

what are the four bases

A
  • adenine
  • thymine
  • guanine
  • cytosine
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7
Q

what are each of the bases bonded to and what is it termed

A
  • each base is bonded to a deoxyribose

- each of these are termed nucleoside

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8
Q

what is each nucleoside bonded to and what is it termed

A
  • each nucleoside is bonded to a phosphate

- each termed as nucleotide

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9
Q

what do the nucleotides form

A
  • form a phosphate backbone
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10
Q

what does the sequence of the four nucleotides determine

A
  • determines the sequence of every protein in the cell, which determine the function of the cell
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11
Q

explain anti parallel chain

A
  • two strands of nucleotides line up opposite each other with each string going in opposite directions
  • one going 5’ - 3’ and the other going 3’ - 5’
  • the structure of the bases only allow adenine to be opposite thymine and guanine to be opposite cytosine
  • this allows the maximum amount of bonds to be formed
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12
Q

what is double helix and what does this result in

A
  • the two strands are coiled into a double helix
  • this gives stability
  • the bases are protected by the sugar phosphate backbone
  • very long
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13
Q

why do dna strands coil up and what is formed

A
  • dna molecule is v big
  • so it coils up more, wrapped around proteins called histones forming a nucleosome
  • nucleosomes coils up forming solenoid
  • all together this is termed chromatin
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14
Q

in dividing cells what happens to chromatin

A
  • chromatin condenses further around scaffold proteins to from chromosomes
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15
Q

how many chromosomes does each human diploid cell have

A
  • 46 chromosomes termed 2n

- 22 pairs of of chromosomes (autosomal) plus 2 sex chromosomes

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16
Q

what are the steps involved when a cell is preparing to divide

A
  • dna needs to be replicated (dna replication)
  • it is done by small sections of dna unwinding to form ‘bubbles’ that allows the enzyme DNA polymerase to copy each of the strands of DNA
  • the new strand of DNA is then paired with its template parental dna strand and separates into the new daughter cell
  • semi conservative replication
  • DNA polymerase are proof reading enzymes therefore able to correct errors
17
Q

what is a gene

A

encodes for a protein

18
Q

what are egg and sperm cells termed as

A
  • haploid cells, n
19
Q

what do diploid cells contain

A
  • two copies of each chromosome and therefore each gene
20
Q

what are two copies of genes called

A
  • alleles
21
Q

what are alleles significant in

A
  • disease and inheritance
22
Q

explain transcription

A
  • section of dna around the gene must be unwound
  • this separates the strand
  • allowing rna polymerase to get in and synthesise a strand of rna
  • with a sequence complimentary to that of the template dna strand
  • this produces mrna which is then used as the template for synthesising the protein
23
Q

what happens to the introns and how is the mrna modified

A
  • spliced out and a cap and tail are put on it
  • the resulting mature transcripts are then exported from the nucleus through the nuclear pores
  • 5 prime cap - chemical structure is added to one end - interacts with nuclear pore
  • on other end poly a tail attached
24
Q

explain transcription

A
  • mature rna translated into proteins by ribosomes
  • strings of amino acids are formed by specific transfer rna
  • recognising three base codons on the mature mrna
  • each codon specifies a trna molecule covalently bound to a specific amino acid
25
Q

what is a stop codon

A
  • do not code for amino acids therefore stopping translation
  • peptide bonds form between the amino acids bound to the trna forming a polypeptide and when a stop codon is reached the polypeptide is released
26
Q

what happens when dna is mutated

A
  • mutated dna results in mutated rna therefore mutated protein
  • results in disease due to genetic or chromosomal abnormalities
27
Q

oral cancer

A
  • associated with mutation or changes in expression of genes
  • causes cells to divide abnormally therefore leading to a tumour
28
Q

4 uses of dna in medicine

A
  • diagnostics
  • prognostics
  • forensics
  • treatment
29
Q

structure of rna

A
  • single stranded
  • formed by transcription from dna
  • involved in protein synthesis
  • sugar, base, phosphate
  • ribose sugar
  • thymine replaced with uracil
30
Q

what are the three forms of rna

A
  • rRNA (ribosomal)
  • tRNA (transfer)
  • mRNA (messenger)
31
Q

what is rna called that is not coded into proteins

A
  • non coding rna
32
Q

role of enzyme helicase

A
  • causes dna to unwind
33
Q

role of DNA polymerase

A
  • joins unwound strand - brings opposite bases

year 1 - dentistry (24 decks)

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