chapter one: the relationship between nucleic acids and proteins Flashcards

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1
Q

2 monomers of a nucleic acid

A

deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)

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2
Q

state the base pairing rules

A

DNA:

  • Adenine and Thymine
  • Guanine and Cytosine

RNA

  • Adenine and Uracil
  • Guanine and Cytosine
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3
Q

compare DNA and RNA

A

similarities:

  • DNA and RNA are both made up of nucleotide monomers, which contain phosphate, a sugar and a nitrogenous base

differences:

  • DNA contains thymine as a base instead of uracil
  • DNA is double stranded and RNA is single stranded
  • DNA is located in the nucleus whilst RNA is everywhere
  • DNA has a function of instructing and RNA makes proteins
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4
Q

eukaryotic genes features

A

consists of a coding region and flanking regions

  • coding regions: part of a gene that contains the coded information for making a protein —> within the coding regions, it contains exons and introns
  • exons contain the instructions for the synthesis of the protein and are both transcribed and translated —> they provide the instructions that code for the amino acids in the produced protein
  • introns are sections that are no expressed
  • flanking regions: in the upstream and downstream of a gene
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5
Q

define gene regulation

A

gene regulation is when genes are regulated to keep them from producing but not overflood the cell with that gene.

  • the process of turning genes on and off
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6
Q

compare structural and regulatory genes

A

structural genes:

  • codes for proteins that become part of the structure or function of cells

regulatory genes:

  • code for proteins that control the expression of other genes -> their actions determine whether other genes are turned on or off
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7
Q

outline how the trp operon works

A

presense of trp:

  • trp binds to the repressor protein causing a configurational change in its shape → allows it to be active
  • enables the repressor to bind to the operator
  • RNA polymerase is unable to bind to the promoter and transcription does not occur
  • operon is turned off
  • trp isn’t made

absence of trp:

  • repressor is unable to bind to the operator (in an inactive form)
  • rna polymerase can bind to the promoter and start transcription of the structural genes
  • operon is on
  • trp can be made
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8
Q

define the proteome

A

the complete array of proteins produced by a single cell or an organism in a particular environment

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9
Q

describe condensation polymerisation

A
  • the process of joining amino acids together
  • condensation → water/smaller
  • polymerisation → making a polymer
  • amino acids join using energy and water is released
  • carboxyl groups bind with the amino group
  • OH of carboxyl group joins w/ H of the amino group to form water
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10
Q

define polymer

  • state 2 molecules fond in living things that are polymers
A

polymers are what makes up amino acids which makes proteins

  • a large substance made up of smaller subunits
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11
Q

describe the 4 levels of protein structure

A

primary:

  • A linear sequence of amino acids linked together called a polypeptide chain
  • NOT FUNCTIONAL

secondary:

  • consists of alpha helices, beta pleated sheets and random coils
  • the folding and coiling is caused by interactions of the R-group

tertiary:

  • A irregular 3D folding held together by ionic or hydrogen bonds forming a complex shape
  • A FUNCTIONAL STRUCTURE

quaternary:

  • bonding of two or more polypeptide chain
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12
Q

explain why the shape of a protein is important to its function

A
  • allows it to have a specific function in a cell or body structure to interact with other molecules
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13
Q

summaries nucleus

A

codes for the proteins (makes mRNA) which goes to the ribosome on the rough endoplasmic reticulum

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14
Q

summaries rough endoplasmic reticulum

A

the ribosome uses the mRNA code to make a protein, which is then folded and modifies in the rough endoplasmic reticulum

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15
Q

summaries transport vesicle

A

the proteins are placed into a transport vesicle and then moves to the golgi apparatus

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16
Q

summaries golgi apparatus

A

the proteins undergo further modification before being packages into a secretory vesicle

17
Q

summaries secretory vesicles

A

exports the proteins out of the cell (at the cell membrane via exocytosis)

18
Q

summarise plasma membrane

A

the membrane found in all cells that separates the interior of the cell from the outside environment

  • the secretory vesicles move to the plasma membrane and expel its contents through exocytosis
19
Q

describe the 3 forms of RNA

A

mRNA

  • messenger RNA
  • carries genetic message from DNA in the nucleus to ribosomes
  • involved in transcription and translation

tRNA

  • transfer RNA
  • carry SPECIFIC amino acids to ribosomes to be used to construct proteins

rRNA

  • ribosomal RNA
  • works with other proteins to make ribosomes in cytosol
    Subunits that allow for the interaction of mRNA and tRNA. Allows for the growing peptide chain to be created.
20
Q

DNA code is…

A

is universal and redundant

universal:

  • essentially the same across all organisms - bacteria, plants, animal

redundant:

  • different triplets of bases can code for the same amino acid
21
Q

RNA processing

A
  • turns pre-mRNA to mRNA
  • capping of the 5’ end with a methyl cap
  • addition of a poly-A tail on the 3’ end
  • introns are removed and exons are spliced together
22
Q

define operon and operator

A

operon

  • related genes found in a cluster on a chromosome, under the control of a single promoter

operator:

  • short DNA segment found between promoter and gene to be transcribed
23
Q

attenuation

A

Attenuation –prevents the completion of
transcription.

  • levels of tryptophan are high, attenuation causes RNA polymerase to stop prematurely when it’s transcribing the trp operon resulting in a shortened mRNA
  • Specific coding in the attenuator regions allows
    sections known as hairpin loops to form when they are
    transcribed to mRNA
24
Q

difference between exocytosis and endocytosis

A
  • endocytosis involves taking in a substance from outside the cell by engulfing them in a vesicle derived from the cell membrane
  • exocytosis is where cells shift materials, such as waste products, from inside the cell to the extracellular space
25
Q

steps in transcription

A
  1. DNA in the nucleus
  2. That DNA is unzipped and read by RNA polymerase
  3. The polymerase will create a complementary strand (however in MRNA T is replaced WITH U) (THYMINE IS REPLACED BY URACIL)
  4. The strand is called a pre-mature mRNA with exons and introns
  5. A method called excising is used to cut the mRNA sequence to remove introns and splicing is used to glue the exons together
  6. A metal cap and tail (‘5 is the cap and ‘3 is the tail) are placed onto the corresponding ends of the now-matured mRNA
26
Q

steps in translation

A
  1. The strand is exported to ribosomes in the rough endoplasmic reticulum
  2. Once it is there, a ribosome made up of rRNA will attach to the matured mRNA
  3. From there, the mRNA will be read by the ribosomes
  4. They are read in groups of three also called codons
  5. tRNA is free-floating and carries amino acids on the top
  6. Once read, the complementary anticodon will dock and release the amino acid to form a polypeptide chain
27
Q

how can the same gene code for different proteins

A
  • exon shuffling
  • alternate folding
  • golgi modification