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year 12 biology > DNA and Polypeptide Synthesis > Flashcards

DNA and Polypeptide Synthesis Flashcards

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1
Q

what is a prokaryotic cells

A

do not contain a nucleus or any other membrane-bound organelle. Prokaryotes include two groups: bacteria and archaea

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2
Q

what is a eukaryotic cells

A

contain membrane-bound organelles including a nucleus. Eukaryotes can be single-celled or multi-celled. E.g. humans, plants, fungi and insects

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3
Q

define exon

A

gene is expressed, everything codes for a trait

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4
Q

define intron

A

not all DNA codes for a trait

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5
Q

define histone

A

small proteins that DNA is bound around (not in prokaryotes)

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6
Q

what are the difference between prokaryotes and eukaryotes (DNA, nucleus, exons/introns, histones, DNA location, size)

A

PRO
DNA: DNA contained in a single circular chromosome and plasmids (circular DNA)
nucleus: No membrane bound nucleus, called nucleoid instead
exons and introns: exons only
histones: no
DNA location: nucleoid
size: small
EUK
DNA: linear (straight lines) DNA
nucleus: DNA contained in membrane bound nucleus
exons and introns: both
histones: yes
DNA location: DNA found in the nucleus, chloroplast and mitochondria
size: large

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7
Q

similarities of pro and eukaryotes

A

Both have double stranded DNA twisted into a double helix
Both have mRNA which is an intermediate code to build proteins, the base U (uracil) replacing Thymine
Same role - make polypeptides

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8
Q

what is polypeptide synthesis

A

The sequence of the nucleotide bases in genes represents the coded instructions for constructing polypeptides, the building blocks of proteins
The completed protein is the form in which the gene is expressed

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9
Q

what is mRNA

A

Copy of DNA template strand during transcription that then takes these instructions from the nucleus to the ribosomes in the cytoplasm for translation. Each triplet of bases (codon) on the mRNA molecule interacts a tRNA molecule - no ‘T’ in mRNA, always U

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10
Q

outline the process of transcription

A
  1. Enzyme helicase causes the DNA molecule to unzip in the section of a specific gene
  2. Enzyme RNA polymerase adds complementary bases forming the DNA template strand (mRNA) - According to the complementary base pairing rules (Uracil instead of Thymine, U goes with A instead of T going with A)
  3. mRNA strand is formed
  4. mRNA strand travels out the nucleus from the pores and goes into the cytoplasm, DNA winds back together
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11
Q

outline the process of translation

A
  1. Ribosomes move along mRNA strand
  2. mRNA are read in groups of three (codons) in 5’ to 3’ direction
  3. Each codon specifies a particular amino acid
  4. tRNA molecule with complementary base triplet (called an anticodon) bring specific amino acid to ribosome
  5. Amino acids are linked by peptide bonds to form a chain called a polypeptide
  6. Once chain is complete the chain folds to form a complex 3D protein
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12
Q

what is tRNA

A

the molecule that brings amino acids to ribosomes during protein synthesis. The tRNA has an anticodon that matches with the mRNA’s codon and carries a specific amino acid

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13
Q

what is a protein

A

form structure and support to cells, used in transport or as enzymes

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14
Q

what is a codon

A

triplet of bases

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15
Q

what is an anticodon

A

complementary of codons

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16
Q

what is the function of polypeptide synthesis

A

gene expression

17
Q

what is the importance of polypeptide synthesis

A

gene expression could not take place which would result in an organism potentially not functioning normally
proteins necessary for correct structure and function of a cell would not take place
the molecular structure of proteins are completely dependent on the control of polypeptide synthesis

18
Q

what is an example of proving the importance of polypeptide synthesis and proteins

A

some proteins produced are enzymes - which control the metabolism and hence the function of the body, there is also structural proteins - controlling the structure of the body
if an enzyme’s active site is not created properly it will not fit the correct substrate

19
Q

what is the importance of mRNA

A

-Translation would not occurs; the copy of the DNA template strand that takes instructions to the ribosomes in the cytoplasm would not occur
-Hence the gene can not be expressed as the ribosome has nothing to read/transcribed as tRNA can not be activated to transfer amino acids and hence can’t create a polypeptide chain/protein
-Transcription won’t occur

20
Q

what is the importance of tRNA

A

-There would be no molecule that brings amino acids to ribosomes during protein synthesis
-Without amino acids no polypeptide can form and hence no protein can form so genes can’t be expressed

21
Q

what is a genotype

A

set of alleles

22
Q

what is alleles

A

different versions of a gene

23
Q

what is phenotypic expression

A

-observable characters
-the set of characteristics expressed from the genetic information of a cell or the part of the genotype (set of alleles) that has been switched on to allow transcription and translation to produce polypeptides, then proteins
-An organism’s genotype and environment effect its phenotype

24
Q

what are examples of how genes and environments affect phenotypic expression

A

-A tree will not reach its genetic height potential if it does not receive the water and minerals needed
-Hydrangeas petal colour changes to the pH of the surrounding soil (acidic soil petals turn blue, basic soil petals turn pink

25
Q

what is the role of proteins

A

-every function of a living organism depends on proteins
-proteins have a specific amino acids, giving it a unique shape that allows it to carry out its specific function

26
Q

what is the structure of proteins

A

level 1: primary protein structure, polypeptide formation
level 2: secondary structure, polypeptide becomes pleated
level 3: tertiary structure, pleated polypeptide folds into 3D form
level 4: quaternary structure, two or more 3D polypeptide molecules bonded together

27
Q

an example of a protein and its importance

A

Proteins act as catalysts in cellular reactions (enzymes), proteins must be a particular shape to hold the substrate and undergo the particular cellular reactions

year 12 biology (4 decks)

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