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12 Biology > Chapter 2: Nucleic Acids and Proteins > Flashcards

Chapter 2: Nucleic Acids and Proteins Flashcards

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1
Q

What are amino acids, and what role do they play in protein structure?

A

Amino acids are the monomers of proteins. They consist of a central carbon atom, a carboxyl group, an amino group, an R-group, and a hydrogen atom.

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2
Q

How does the R-group of an amino acid contribute to the diversity of proteins?

A

The R-group, or side chain, of an amino acid determines its unique identity. Different R-groups have distinct chemical properties, influencing how amino acids interact within a protein.

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3
Q

What is the primary structure of a protein?

A

The primary structure refers to the sequence of amino acids in a polypeptide chain.

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4
Q

How are amino acids joined together to form proteins?

A

Amino acids are joined through condensation reactions, forming peptide bonds and creating polypeptide chains.

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5
Q

Describe the secondary structure of a protein.

A

The secondary structure involves the folding of a polypeptide chain into alpha-helices, beta-pleated sheets, or random coils, stabilized by hydrogen bonds.

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6
Q

What is the tertiary structure of a protein, and why is it crucial for functionality?

A

The tertiary structure is the overall functional 3D shape of a protein. It is essential for the protein’s function and is formed by interactions and bonds between amino acids and R-groups.

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7
Q

When does a protein exhibit quaternary structure?

A

Quaternary structure occurs when two or more polypeptide chains with tertiary structures join together. Proteins with prosthetic groups may also have quaternary structures.

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8
Q

Provide an example of a protein with quaternary structure and its function.

A

Haemoglobin is a protein with quaternary structure responsible for carrying oxygen in red blood cells. It consists of four polypeptide chains bonded together, each containing a haem prosthetic group.

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9
Q

How does the primary structure influence protein folding?

A

The sequence of amino acids in the primary structure determines how R-groups interact, leading to specific bonding patterns and resulting in the folded tertiary or quaternary structure.

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10
Q

What happens if there are changes to the primary structure of a protein?

A

Changes to the primary structure may prevent correct folding, disrupting the protein’s functionality.

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11
Q

What is the role of ribosomes in protein synthesis?

A

Ribosomes, either free-floating or attached to the endoplasmic reticulum, serve as the site of protein synthesis in cells.

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12
Q

How are proteins involved in gene expression?

A

Gene expression involves the production of proteins through processes like transcription and translation.

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13
Q

functions of proteins

there is 8

A

enxymes
transport
structural (keratin)
defence (antibodies)
Motor (myosin - muscle contraction)
storage
receptors (hormore receptor)
hormones (insulin)

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14
Q

What is the proteome, and why is it important in understanding proteins?

A

The proteome refers to all the proteins expressed by a cell or organism at a given time. It is crucial for understanding the functional diversity of proteins and their roles in living organisms.

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15
Q

What is the significance of the condensation reaction in protein synthesis?

A

The condensation reaction joins amino acids, forming peptide bonds and resulting in the formation of polypeptide chains, the building blocks of proteins.

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16
Q

What is the fundamental role of nucleic acids in living organisms?

A

Nucleic acids serve as information molecules, storing genetic instructions and aiding in the production of proteins.

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17
Q

What are the two types of nucleic acids, and what are their roles?

A

The two types of nucleic acids are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). DNA stores genetic information, while RNA is involved in protein synthesis.

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18
Q

Define nucleic acid and polymer.

A

Nucleic acid is a macromolecule encompassing DNA and RNA, while a polymer is a large molecule made up of small, repeated monomer subunits.

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19
Q

What are the components of a nucleotide, and how do they contribute to the structure of nucleic acids?

A

A nucleotide consists of a phosphate group, a five-carbon sugar, and a nitrogen-containing base. The arrangement of these components forms the basic structure of nucleic acids.

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20
Q

3 marks

Describe the structure of a nucleotide,

A

A nucleotide comprises a phosphate group, a five-carbon sugar (ribose in RNA and deoxyribose in DNA), and a nitrogenous base. The phosphate group links the sugar and base, forming the backbone of nucleic acids.

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21
Q

Explain the directional nature of nucleic acids and the significance of the 3’ and 5’ ends.

A

Nucleic acids have a directional nature due to the arrangement of carbons in the sugar. The 3’ end attaches to the phosphate of the following nucleotide, and the 5’ end attaches the sugar to the phosphate group, contributing to the directionality.

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22
Q

What is the role of phosphodiester bonds, and how are they formed?

A

Phosphodiester bonds are strong covalent bonds that link nucleotides in a polymer. They are formed through condensation reactions between the sugar group of one nucleotide and the phosphate group of another.

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23
Q

Differentiate between DNA and RNA in terms of structure, sugar type, and nucleotide bases.

A

DNA is double-stranded, contains deoxyribose sugar, and has thymine (T) as a base. RNA is single-stranded, contains ribose sugar, and has uracil (U) as a base.

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24
Q

How does complementary base pairing contribute to the structure of DNA, and what are the base pairing rules?

A

Complementary base pairing forms hydrogen bonds between nucleotides. Adenine pairs with thymine (A-T), and guanine pairs with cytosine (G-C).

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25
Q

Explain the structure of DNA,

A

DNA consists of two antiparallel polynucleotide chains joined by complementary base pairing, forming a double helix. The helix is further coiled around histone proteins, creating chromosomes

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26
Q

Contrast the structures of DNA and RNA,

A

DNA contains deoxyribose sugar, thymine (T), and is double-stranded. RNA contains ribose sugar, uracil (U), and is single-stranded.

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27
Q

Define phosphodiester bond.

A

A strong covalent bond linking a five-carbon sugar to a phosphate group, forming the sugar-phosphate backbone in nucleic acids.

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28
Q

What is the genome?

A

The complete set of DNA housed within an organism.

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29
Q

What are the properties of the genetic code?

A

unambiggouout
univeral
nonoverlapping

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30
Q

Name the key regions of a gene

A

Promoter, Introns, Exons, Termination sequence, Operator, Leader.

31
Q

Promotor

A

located at the 5’ end, it is where RNA polymerase binds, it initated trasncription

32
Q

introns

A

non-coding regions that are found within genes, they are removed duirng RNA processing during splicing, only eukaryotic genes have introns.

33
Q

exons

A

exons are coding regions within a gene and they are transcribed and translated into the protein produced. they have info to build functional proteins , they are found in both eukaryotic and prokaryotic

34
Q

termination sequence

A

signals the end of transcription, when rna polymerase reaches the termination sequence the mRNA molecule is released.

35
Q

operator

A

is found in the prokaryotic genes and serves as the binding site for ht erepressor proteins, they bind to the operator with inhibits gene expression stoping trasncription

36
Q

leader

A

is the section located just up from the coding region following the promotor and operator, controlling the initiation of transcription

37
Q

universal

A

Nearly all living organisms use the same codons to code for specific amino acids, indicating a universal nature of the genetic code.

38
Q

Unambiguous:

A

Each codon codes for one specific amino acid. For example, the codon UUA only codes for leucine.

39
Q

Degenerate:

A

multiple codons can code for the same amino acid, providing redundancy. For instance, both UUA and UUG code for leucine.

40
Q

Non-overlapping:

A

Each triplet or codon is read independently without overlapping with adjacent triplets or codons.

41
Q

What are the key stages of gene expression involved in the production of proteins?

A

The key stages of gene expression include transcription, RNA processing, and translation.

42
Q

What is transcription, and what is its primary purpose in gene expression?

A

Transcription is the first stage of gene expression, involving the creation of pre-mRNA by converting the genetic information from DNA into RNA. Its purpose is to produce an intermediary molecule (pre-mRNA) that can leave the nucleus and transport the genetic code for protein synthesis around the cell.

43
Q

What is RNA processing, and where does it occur?

A

RNA processing, or post-transcriptional modifications, occurs in eukaryotic cells in the nucleus. It involves modifying pre-mRNA into mature mRNA, including the addition of a 5’ methyl-G cap, a 3’ poly-A tail, and splicing of exons.

44
Q

What is splicing, and what is alternative splicing?

A

Splicing is the process of cutting out introns and joining exons in pre-mRNA. Alternative splicing allows a single gene to produce multiple mRNA strands by selectively including or excluding exons.

45
Q

What is translation, and where does it take place?

A

Translation is the process of converting mRNA into a polypeptide chain. It occurs at ribosomes, either in the cytosol or attached to the rough endoplasmic reticulum.

46
Q

Transcription

A
  1. Transcription factors bind to the promoter region.
  2. RNA polymerase binds to the promoter.
  3. DNA unwinds and unzips
  4. RNA polymerase reads the template DNA strand.
  5. Complementary RNA nucleotides are added to synthesize pre-mRNA.
  6. Pre-mRNA is synthesized in a 5’ to 3’ direction.
  7. RNA polymerase reaches the termination sequence.
  8. Transcription ends, and RNA polymerase detaches.
  9. Pre-mRNA is released.
47
Q

rna processing

A
  1. 5’ Methyl-G cap is added to the 5’ end.
  2. 3’ Poly-A tail is added to the 3’ end.
  3. Introns (non-coding regions) are removed.
  4. Exons (coding regions) are spliced together by a spliceosome.
48
Q

translation

A
  1. mRNA binds to the ribosome.
  2. Start codon (AUG) is recognized.
  3. tRNA with anticodon UAC binds, carrying the amino acid methionine.
  4. mRNA is fed through the ribosome.
  5. tRNA with complementary anticodons delivers specific amino acids.
  6. Peptide bonds form between adjacent amino acids.
  7. Ribosome reaches a stop codon.
  8. Translation ends.
  9. Polypeptide chain is released.
49
Q

What is gene regulation?

A

Gene regulation is the control of gene expression, typically achieved by switching transcription on or off.

50
Q

What is gene expression?

A

Gene expression is the process of reading the information stored within a gene to create a functional product, typically a protein.

51
Q

Define structural gene.

A

A structural gene is a segment of DNA that codes for proteins involved in the structure or function of a cell or organism.

52
Q

Define regulatory gene.

A

A regulatory gene is a segment of DNA responsible for producing proteins that control the expression of other genes.

53
Q

How does gene regulation conserve energy in cells?

A

Gene regulation prevents unnecessary production of gene products such as proteins when they are not required, conserving energy.

54
Q

What is the trp operon?

A

The trp operon is a series of genes within certain bacteria that encode for the production of the amino acid tryptophan.

55
Q

What is the role of the regulatory gene in the trp operon?

A

The regulatory gene controls the expression of the structural genes, preventing unnecessary production of tryptophan.

56
Q

Explain repression in the trp operon.

A

Repression occurs when high levels of tryptophan activate the repressor protein, inhibiting transcription of the trp operon.

57
Q

Describe attenuation in the trp operon.

A

Attenuation is the premature ceasing of transcription when tryptophan levels are high, controlled by the folding of mRNA into a terminator hairpin loop.

58
Q

What is the purpose of the operator in an operon?

A

The operator is a short region of DNA that interacts with repressor proteins, altering transcription of an operon.

59
Q

How do regulatory genes control gene expression?

A

Regulatory genes produce proteins (repressor or activator) that bind to the operator region, influencing transcription of structural genes.

60
Q

Why is gene regulation important for cells?

A

Gene regulation ensures that cells produce appropriate proteins, preventing unnecessary production and maintaining stable energy levels.

61
Q

Compare structural genes and regulatory genes.

A

Structural genes code for proteins involved in cell structure/function, while regulatory genes produce proteins controlling the expression of other genes.

62
Q

What is the Protein Secretory Pathway?

A

The Protein Secretory Pathway is a cellular process that involves various organelles in the production, folding, modification, and packaging of proteins for export from the cell through exocytosis.

63
Q

What is the primary purpose of the Protein Secretory Pathway?

A

The primary purpose of the Protein Secretory Pathway is to export proteins produced within the cell to be used elsewhere in the body.

64
Q

Name the organelles involved in the Protein Secretory Pathway.

A

The organelles involved in the Protein Secretory Pathway include the ribosomes, rough endoplasmic reticulum (RER), Golgi apparatus, and transport and secretory vesicles.

65
Q

What is the role of ribosomes in the Protein Secretory Pathway?

A

Ribosomes synthesize proteins by assembling polypeptide chains from amino acids through the translation of mRNA.

66
Q

Where is the rough endoplasmic reticulum (RER) located, and what is its function?

A

The RER is a membranous organelle attached to ribosomes. It folds and transports proteins, ensuring correct folding before passing them to the Golgi apparatus.

67
Q

What is the function of transport vesicles in the Protein Secretory Pathway?

A

Transport vesicles carry proteins from the rough endoplasmic reticulum to the Golgi apparatus.

68
Q

Describe the Golgi apparatus’ role in the Protein Secretory Pathway.

A

The Golgi apparatus modifies and packages proteins, adding or removing chemical groups, and then packages them into secretory vesicles for export.

69
Q

What is the process of exocytosis, and why is it important in the Protein Secretory Pathway?

A

Exocytosis is the release of vesicle contents from a cell. It is crucial for exporting large substances, such as proteins, out of the cell during the Protein Secretory Pathway.

70
Q

Explain the stages of exocytosis.

A

A vesicle containing secretory products is transported to the plasma membrane.
The membrane of the vesicle fuses with the plasma membrane.
Secretory products are released from the cell into the extracellular environment.

71
Q

What are secretory vesicles, and what is their role in the Protein Secretory Pathway?

A

Secretory vesicles transport proteins for export. They bud off the Golgi apparatus, travel through the cytoplasm, and release proteins into the extracellular environment through exocytosis.

72
Q

How does the Protein Secretory Pathway contribute to cellular energy requirements?

A

Energy for the Protein Secretory Pathway is generated by mitochondria through aerobic cellular respiration, providing ATP needed for the transport of vesicles and modification of proteins.

73
Q

Which organelle is considered the mastermind behind the Protein Secretory Pathway, and what is its function?

A

The Golgi apparatus is the mastermind, modifying and packaging proteins received from ribosomes, ultimately preparing them for export from the cell.

74
Q
A

12 Biology (9 decks)

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