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Higher Human Biology Key Terms > Unit 1: Human Cells: Chapter 3: Gene Expression > Flashcards

Unit 1: Human Cells: Chapter 3: Gene Expression Flashcards

1
Q

Cell genotype

A

Genetic constitution of a cell. Determined by the sequence of DNA bases in the genes (genetic code).

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2
Q

Phenotype

A

Sum total of physical and physiological characteristics. Determined by the proteins that are synthesized when the genes are expressed.

Final phenotype is result of information held in the genotype & environmental factors.

Genotype + Environment = Phenotype

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3
Q

Nucleic acid

A

There are 2 types of nucleic acid

DNA - deoxyriboenucleic acid
RNA - ribonucleic acid

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4
Q

RNA nucleotide

A

Each RNA nucleotide is made up of a

  • a molecule of ribose sugar
  • an organic base
  • a phosphate group
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5
Q

In RNA which base replaces thymine?

A

Uracil

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6
Q

Name 3 ways in which DNA and RNA differ.

A

DNA is double stranded. RNA has only a single strand.
Complementary base partner of adenine is thymine in DNA uracil in RNA.
Sugar molecule in DNA is Deoxyribose; in RNA it is Ribose.

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7
Q

Put the following in order of size from smallest to largest

  • Protein
  • Amino acid
  • Enzyme
  • Polypeptide chain
A
  1. Amino acid
  2. Polypeptide chain
  3. Protein
  4. Enzyme
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8
Q

Describe the function of genetic instructions & how they work

A

Genetic instructions control an organism’s inherited characteristics. They are contained in the sequences of bases along the DNA strands in the cell nucleus. Characteristics are determined by biochemical processes controlled by enzymes. Enzymes are made of proteins whose exact molecular structure, shape & ability to perform its specific function all depend on the sequence of its amino acids. This critical order is determined by the order of bases in the organism’s DNA.
SO DNA controls the structure of enzymes & in so doing determines an organism’s inherited characteristics.

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9
Q

What are the 4 bases in DNA?

A

Adenine
Cytosine
Guanine
Thymine

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10
Q

How many types of amino acids are their in proteins?

A

20

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11
Q

How may bases are there in any given group?

A

3.

Bases are grouped in triplets of one or more of 64 combinations.

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12
Q

Ribosome

A

Roughly spherical structure within cytoplasm of cell where amino acids are assembled to synthesize proteins. Contain rRNA & enzymes essential for protein synthesis.

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13
Q

mRNA

A

Messenger RNA (formed from appropriate section of DNA strand and carries information to ribosomes). As result of the base pairing rule, each mRNA molecule receives a nucleotide sequence complementary to the DNA template strand.

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14
Q

tRNA

A

Transfer RNA (receives mRNA information at ribosome and translates the genetic information for protein synthesis within the ribosome. Composed of a single strand of nucleotides.

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15
Q

Transcription

A

Synthesis of mRNA from a section of DNA. Transcription is initiated at a ‘promoter’ region of DNA strand.

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16
Q

RNA polymerase

A

Enzyme responsible for catalyzing transcription. It moves along the DNA unwinding & opening up the strand by breaking the hydrogen bonds between the base pairs, to bring about synthesis of an mRNA molecule.

17
Q

Intron

A

Long section of DNA within a gene not involved in coding for polypeptide chain.

18
Q

Exon

A

Much smaller region of DNA strand within gene which codes for polypeptide.

19
Q

Primary mRNA transcript

A

First strand of mRNA molecule replicated from DNA template, containing both intron and exon sections.

20
Q

Mature mRNA transcript

A

mRNA strand that has had introns spliced out and remaining exons joined together to form a continuous sequence of nucleotides.

21
Q

Alternative segment RNA

A

Under certain circumstances, alternative segments of primary mRNA transcript can be treated as exons & introns. Same primary transcript has potential to produce several mature mRNA transcripts each with different sequence of base triplets & each coding for different polypeptide.
i.e. one gene can code for several different proteins & a limited number of genes can give rise to a wide variety of proteins.

22
Q

Splicing

A

Process by which intron sections of primary mRNA transcript are cut out & removed from molecule to leave just exon sections, which code for a polypeptide chain.

23
Q

Translation

A

Synthesis of protein as a polypeptide chain under direction of mRNA.

24
Q

Codon

A

Basic unit of genetic code. Base triplet in mRNA molecule carrying genetic message to ribosome. Each codon is complementary to a triplet of bases on original template DNA strand.

25
Q

Anticodon

A

Particular triplet of bases on tRNA molecule exposed complementary to an mRNA codon with a specific amino acid at tRNA attachment site.

26
Q

rRNA

A

ribsome Ribonucleic Acid

27
Q

Function of ribosome

A

To bring tRNA molecules bearing amino acids into contact with mRNA. Contains one binding site for mRNA and 3 binding sites for tRNA.

28
Q

tRNA binding sites - P, A & E

A
  • site P holds the tRNA carrying the growing polypeptide chain.
  • site A holds the tRNA carrying the next amino acid to be joined to the growing chain by a peptide bond.
  • site E discharges a tRNA from the ribosome once its amino acid has become part of the polypeptide chain.
29
Q

Start codon

A

First base triplet in mRNA molecule which positions at P binding site in ribosome. Molecule of tRNA with its amino acid attaches at binding site P with hydrogen bonds between the mRNA start codon and the tRNA anticodon. Once 2 amino acids are adjacent they are joined by a peptide bond to the growing polypeptide chain.

30
Q

Peptide bond

A

Means by which amino acids are joined to form polypeptide chains.

31
Q

Stop codon

A

Region on mRNA strand which stops formation of polypeptide chain.

32
Q

Proteins

A

All proteins contain carbon, hydrogen, oxygen & nitrogen. Many also contain sulphur. Each protein is built up of a widely varying number of subunits called amino acids.
Proteins are found in the membranes of all living cells & of cell organelles.

33
Q

Polypeptide

A

Chain of linked amino acids

34
Q

Enzymes

A

Each enzyme molecule is made of protein & folded in a way to expose an active surface to facilitate combining with a specific substrate.

35
Q

Intracellular enzymes (enzymes inside cells)

A

Speed up the rate of biochemical processes such as respiration & protein synthesis & therefore essential l for the maintenance of life.

36
Q

Hormones

A

Chemical messengers made of protein in blood to ‘target’ tissues where they exert a regulatory effect on growth and metabolism.

37
Q

Antibodies

A

Made of proteins & have a characteristic Y shape, produced by white blood cells to defend body against antigens.

Higher Human Biology Key Terms (7 decks)

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