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Biology 30 > Molecular Genetics: Chapters 17-20 > Flashcards

Molecular Genetics: Chapters 17-20 Flashcards

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1
Q

Phoebus Levene contributions to DNA

A
  • Isolated two types of nucleic acid, DNA (deoxyribose nucleic acid) and RNA (ribose nucleic acid)
  • Proved that chromosomes are made up of DNA and proteins
  • Genes are located on the chromosome
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2
Q

Frederick Griffith contributions to DNA

A

• Studied the pathogenic (disease-causing) bacteria that was responsible for pneumonia
- Used dead Streptococcus pneumoniae bacteria as control. This dead bacteria still passed their pathogenic properties to live, non-pathogenic bacteria. This created the transforming principle.

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3
Q

Transforming principle

A

• Ability of dead pathogenic bacteria to pass on their disease-causing properties to live, non-pathogenic bacteria.

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4
Q

Oswald Avery, Colin MacLeod, and Maclyn McCarty contributions to DNA

A

→ Expanded on Griffith’s transforming principle to determine what was the agent of
transformation.
• When they treated heat-killed pathogenic bacteria with a protein-destroying enzyme, transformation still occurred.
• When they treated heat-killed pathogenic bacteria with a DNA-destroying enzyme, transformation did not occur.

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5
Q

Alfred Hershey and Martha Chase contributions to DNA

A

→ Wanted to determine whether viral protein or viral DNA was responsible for taking over the genetic machinery of the host cell.
• Used radioactive labelling to show that genes are made up of DNA. Scientists knew that virtually all of the phosphorus present in the T2 virus is in its DNA, while sulphur is found only in its protein coat. Prepared two different samples of the T2 virus, one tagged with radioactive phosphorus and other with radioactive sulfur. Bacterial cells that were infected by viruses with radioactive DNA were radioactive, indicating that the viral DNA entered the host cell. In contrast, bacterial cells that were infected by viruses with radioactive protein coats were not radioactive, indicating that no viral protein entered the host cell. Therefore, DNA must direct the cell to produce new viruses.
• The T2 bacteriophage consists of a protein coat surrounding a length of DNA. The virus attaches to a bacterial cell and injects genetic information into the cell. The infected cell manufactures new viruses and bursts, infecting other cells
→ Concluded that viral DNA, not viral protein, enters the bacterial cell.

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6
Q

Rosalind Franklin contributions to DNA

A

Used x-ray photography to analyze the structure of DNA.

  • Concluded that DNA is a helical structure with two regularly repeating patterns, one recurring at intervals of 0.34nm, and the other with intervals of 3.4nm.
  • Also observed how DNA reacted with water and concluded that the nitrogenous bases were located on the inside of the helical structure, and the sugar-phosphate backbone was located on the outside, facing toward the watery nucleus of the cell.
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7
Q

DNA (deoxyribonucleic acid)

A

Nucleic acid molecule that governs the processes of heredity in all plant and animal cells.

  • Made up of long chains of individual units that Levene called nucleotides.
  • Both DNA and RNA contain a combination of four different nucleotides.
  • Each DNA nucleotide is composed of a five-carbon sugar, a phosphate group, and one of five nitrogen-containing bases.
  • The four bases that are found in nucleotides are adenine (A), guanine (G), cytosine (C), and thymine (T). (RNA has the base uracil (U) instead of thymine). Scientists identify the nucleotides by referring to their bases: A, G, C, T for DNA, and A, G, C, and U for RNA.
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8
Q

Nucleotides

A

Units making up nucleic acids (ex. DNA, RNA), composed of a five-carbon sugar, a phosphate group, and one of five nitrogen-containing bases (adenine, cytosine, guanine, and either thymine or uracil).
- Levene determined that nucleic acids are made up of long chains of nucleotides. (He also incorrectly thought that nucleotides were present in equal amounts and that they appeared in these chains in a constant and repeated sequence.

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9
Q

Chargaff’s rule

A

Created by Erwin Chargaff. In any sample of DNA, a constant relationship in which the amount of adenine is always approximately equal to the amount of thymine, and the amount of cytosine is always approximately equal to the about of guanine.
• A ~ T
• C ~ G

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10
Q

James Watson and Francis Crick contribution to DNA

A

First to produce a structural model of DNA that could account for experimental evidence. They created the double-helix model.
• DNA is a thread-like molecule, made up of two long strands of nucleotides that are bound together in a spiral shape; the double-helix. If the helix was unwound, the DNA molecule would look like a ladder.
- The “handrails” of the ladder are the sugar-phosphate backbones of the two nucleotide strands. The “rungs” are the bases that protrude inward at regular intervals along each strand.
• Knew that sugar-phosphate handrails remained constant over the length of the molecule. However, the nitrogenous bases are different sizes.
- Adenine and guanine are derived from purine compounds, which have a double-ring structure.
- Thymine and cytosine are derived from pyrimidines, which have a single-ring structure.
- Using Chargaff’s rule, Watson and Crick hit up on the idea that an A nucleotide on one chain always sits across from a T nucleotide on the other chain, while a C nucleotide on one chain always sits across from a G nucleotide on the other chain. The A-T and C-G pairs are complementary pairs that are hydrogen-bonded.
- The handrails maintain a constant total distance of three rings.
- The two strands of DNA that make the double helix are not identical. They are complementary to each other, and are antiparallel. You can always deduce the base sequence on one strand from the base sequence on the other strand. Phosphate bridges run in opposite directions in two strands. Each end of a double-stranded DNA molecule contains the 5’ end of one strand and the 3’ end of the complementary strand. **This is important for DNA replication and protein synthesis.

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11
Q

Antiparallel

A

Describes the property by which the 5’ to 3’ phosphate bridges run in opposite directions on each strand of nucleotides in a double-stranded DNA molecule.

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12
Q

Similarities between DNA and RNA

A
  • Are both nucleic acids
  • Found in most bacteria
  • Found in the nuclei of most eukaryotic cells
  • Similar structures
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13
Q

Differences between DNA and RNA

A
  • The sugar component of RNA is ribose rather than deoxyribose.
  • RNA doesn’t have the nucleotide (T). Instead it is the nucleotide uracil (U).
  • RNA remains single-stranded, although the single strand can sometimes fold back on itself to produce regions of complementary base pairs.
  • RNA molecule can assume different structures which results in several types of RNA, each serving a different function.
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14
Q

Gene

A

Functional subunit of DNA that directs the production of one or more polypeptides (protein molecules).
* Genes are not spaced regularly among chromosomes.

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15
Q

Genome

A

Sum of all the DNA that is carried in each cell of the organism. This DNA includes genes as well as regions of noncoding DNA which can play a part in gene expression.

  • There is no relationship between the number of genes in an organism and the total size of its genome.
  • The total human genome is about three billion base pairs, ~20 000 to 25 000 genes.
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16
Q

Replication

A

In genetics, refers to the reproduction of an exact copy of genetic material, a cell, or an organism.
- Cell replicates its entire genome in the S phase, and only once in the whole cell cycle. Only has an error rate of about one per one billion nucleotide pairs.

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17
Q

Semi-conservative

A

Term used to describe replication: each new molecule of DNA contains one strand of the original complementary DNA and one new strand, thus conserving half of the molecule.
- The process of replication is called a sequence, but actually takes place simultaneously.

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18
Q

Process of DNA replication

A
  • Starts at a specific nucleotide sequence, aka the replication origin
  • Enzymes called helicases bind to the DNA at the replication origin.
  • Helicases cleave and unravel a short segment of the double helix
  • Two Y-shaped areas are created (replication fork) at the each end of the unwound area which creates a replication bubble.
  • Molecule is ready for replication
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19
Q

Elongation and Termination of DNA replication

A
  • The enzyme DNA polymerase attaches to new nucleotides to the free 3’ hydroxyl end of a pre-existing chain of nucleotides.
  • DNA polymerase starts at a RNA primer, which initiates the process of replication
  • Elongation only occurs at the 5’ - 3’ direction, which is the leading strand, which is replicated continuously
  • The lagging 3’ - 5’ strand is replicated in short segments, backwards. The DNA synthesized on the lagging strand in short segments are Okazaki fragments.
  • Okazaki fragments are spliced together by DNA ligase.
  • Termination occurs, and the result is two new DNA strands and dismantling of the replication machine.
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20
Q

Leading strand

A

In DNA replication, the 5’ - 3’ strand that is replicated continuously

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21
Q

Lagging strand

A

In DNA replication, the 3’ - 5’ strand that is replicated in short segments (Okazaki fragments)

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22
Q

Okazaki fragments

A

Short nucleotide fragments synthesized during DNA replication of the lagging strand

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23
Q

DNA ligase

A

Enzyme that splices together Okazaki fragments during DNA replication on the lagging strand. Also proofreads each nucleotide, determining whether or not hydrogen bonding has taken place between the base and new strand. (No hydrogen bond indicates mismatch between bases)

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24
Q

Replication machine (RM)

A

Complex involving dozens of different enzymes and other proteins that work closely together in the process of DNA replication and interact at the replication fork.

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25
Q

Termination

A

In DNA replication, the completion of the new DNA strands and the dismantling of the replication machine.

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26
Q

Primase

A

Synthesizes an RNA primer to begin the elongation process.

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27
Q

Gene expression

A

The transfer of genetic information from DNA to RNA to protein. The flow of genetic information from DNA to RNA to protein is aka the “central dogma” of gene expression.

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28
Q

Transcription

A

The first stage of gene expression, in which a strand of messenger RNA (mRNA) is produced that is complementary to a segment of DNA. DNA is copied into the mRNA. Takes place in the nucleus of a eukaryotic cell.

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29
Q

Translation

A

The second stage of gene expression, in which the mRNA nucleotide sequence directs the synthesis (coming together) of a polypeptide (a chain of amino acids) with the aid of another molecule, transfer RNA (tRNA).

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30
Q

Messenger RNA (mRNA)

A

Strand of RNA that carries genetic information from DNA to the protein synthesis machinery of the cell during transcription.

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31
Q

Transfer RNA (tRNA)

A

Type of RNA that works with mRNA to direct the synthesis of a polypeptide in translation.

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32
Q

Genetic code

A

The order of base pairs in a DNA molecule.

  • Base pairs are made up of amino acids.
  • Determines how the amino acids are strung together and how the proteins are made. *The order of nucleotides in a gene provides the information, written in genetic code, that is necessary to build a protein.
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33
Q

Amino acids

A

An organic compound consisting of a carboxylic acid group (COOH) an amino group (NH2), and any various side groups, linked together by peptide bonds to form proteins.

  • Specific sequence of amino acids determine the chemical properties of each protein.
  • Are what make up proteins, which determine the structure, function and development of the cell and are responsible for inherited traits.
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34
Q

Codon

A

In a gene, each set of three bases (e.g. ACC or GAA) that code for an amino acid or a termination signal.

  • Genetic code is always interpreted in terms of the mRNA codon rather than the nucleotide sequence of the original DNA strand.
  • The three codon letters identifies the amino acid that responds to the codon.
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35
Q

Start codon and amino acid

A

AUG - Methionine

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36
Q

Stop codons

A

UAA, UAG, and UGA

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37
Q

Three characteristics of the genetic code

A
  • The genetic code is redundant, that is, more than one codon can code for the same amino acid. Only three codons do not code for any amino acid. (These codons serve as “stop” signals to end protein synthesis.
  • The genetic code is continuous, that is, the genetic code reads as a series of three-letter codons without spaces, punctuation, or overlap. Knowing exactly where to start and stop translation is essential. A shift of one or two nucleotides in either direction can alter the codon groupings and result in an incorrect amino acid sequence.
  • The genetic code is nearly universal. Most living organisms build proteins with the genetic code. *Important for gene technology
38
Q

Transcription process

A
  • The sense strand (strand of double-stranded DNA that is transcribed) of a gene is used as a template to synthesize a strand of messenger RNA (mRNA).
  • Transcription takes place in the nucleus.
  • A double helix opens when the RNA polymerase complex has bound to the sense strand of the DNA molecule.
  • Enzymes work their way along the DNA molecule and synthesize a strand of mRNA that is complementary to the sense strand of DNA. (In mRNA strand, base thymine is replaced with uracil.)
  • RNA polymerases work in the 5’ to 3’ direction, adding each new nucleotide to the 3’-OH group of the previous nucleotide.
  • There is no need for Okazaki fragments as RNA polymerases transcribe only one strand of the template DNA.
  • A specific nucleotide sequence in template DNA serves as a signal to stop transcription. When RNA polymerases reach the signal, they detach from the DNA strand. New mRNA strand is released from the transcription assembly and the DNA double helix reforms.
  • RNA moves towards cytoplasm
39
Q

Translation process

A 
- In order for a cell to create its needed proteins, codons must be translated along a stretch of mRNA into amino acid sequences. This requires both a chemical translator and a set of cellular protein synthesis equipment. Once the mRNA reaches the cytoplasm, the translator protein and protein synthesis equipment work together to assemble the proteins.
Transfer RNA (tRNA) is the molecule that links each mRNA codon to its specific amino acid. It is made up of a single strand of RNA that folds into a certain shape.
The bottom lobe of tRNA contains the anticodon.
40
Q

Translation cycle

A

Translation is activated when mRNA molecule binds to active ribosome complex, and binds in a way that two adjacent codons are exposed. The first tRNA molecule carrying the amino acid methionine, base-pairs with the first exposed mRNA codon - the start codon, AUG. Once the tRNA and mRNA are in place, translation follows a cycle of three steps:

  1. A second loaded tRNA molecule arrives at the codon adjacent to the first tRNA.
  2. Enzymes catalyze the formation of a chemical bond that joins the amino acid carried by the first tRNA to the amino acid carried by the second tRNA. At the same time, the amino acid chain is transferred from the first tRNA to the second tRNA.
  3. The ribosome moves a distance of one codon along the mRNA strand. The first tRNA molecule detaches from the mRNA and picks up another amino acid. The second tRNA now holds a growing amino acid chain. A third tRNA molecule arrives at the newly-exposed codon next to the second tRNA, and the cycle repeats.
    - The translation cycle continues until a stop codon is reached. The completed polypeptide is then released, and the ribosome assembly comes apart.
41
Q

Anti-codon

A

pecialized base triplet located on one lobe of transfer RNA (tRNA) molecule that recognizes its complementary codon on a messenger RNA (mRNA) molecule.

42
Q

Ribosomes

A

Ribosomes are the main structures of the protein synthesis equipment. Ribosomes bring together the mRNA strand, the tRNA molecules carrying the amino acids, and enzymes needed to build polypeptides. Ribosomes also contain ribosomal RNA (rRNA).

43
Q

Ribosomal RNA (rRNA)

A

Linear strand of RNA that remains associated with the ribosomes

44
Q

Genomics

A

Study of entire genomes, including the interactions among multiple genes.
- Allows the study of interactions among genes and regulatory proteins that contribute to particular disorders.

45
Q

Proteomics:

A

Study of all the proteins that are produced by a given genome.
- Allows the study of interactions among genes and regulatory proteins that contribute to particular disorders.

46
Q

Mutation

A

Permanent change in the genetic material of an organism.

  • All mutations are inheritable, they are copied during DNA replication and passed onto daughter cells.
  • Not all mutations are passed onto future generations. Only mutations that affect the genetic information in the gametes of an organism are passed onto the organism’s offspring.
47
Q

Somatic cell mutations

A

Permanent change in the genetic material of a somatic (body) cell, not including germ cells, during the lifetime of an organism; is copied during DNA replication and passed onto daughter cells, but not passed onto future generations.
- Key cause of cancer

48
Q

Germ line mutation

A

Permanent change in the genetic material of a reproductive cell during the lifetime of an organism that is passed onto future generations.

49
Q

Point mutations

A

Permanent change in the genetic material of a cell that affects one or just a few nucleotides; may involve the substitution of one nucleotide for another, or the insertion or deletion of one or more molecule.
- Point mutation with a nucleotide substitution can have a minor effect on cell’s metabolism due to the redundancy of the genetic code. A change in coding sequence does not always result in change to the polypeptide product. (ex. CCT to CCC is still glycine.)

50
Q

Silent mutations

A

Permanent change in the genetic material of a cell that has no effect on the function of the cell.

51
Q

Nonsense mutations

A

Permanent change in the genetic material of a cell that renders a gene unable to code for a functional protein.

  • Due to a nucleotide substitution that affects a regulatory sequence. May result in the cell being unable to respond to metabolic signals.
  • Ex. Changing UUG to UAG, a stop codon, causing premature stops and no functional polypeptide can be produced.
52
Q

Missense mutation

A

Permanent change in the genetic material of a cell that results in a slightly altered but still functional protein.
- Can be harmful. Ex. A change in a single amino acid in one of the polypeptides that makes up hemoglobin is responsible for sickle cell disease.

53
Q

Frameshift mutation

A

Permanent change in the genetic material of a cell caused by the insertion or deletion of one or two nucleotides so that the entire reading frame of the gene is altered; usually results in a nonsense mutation.
- When a nucleotide is inserted or deleted, and it changes the polypeptide (amino acid name) entirely.

54
Q

Chromosomal mutation

A

Mutations that involve a rearrangement of genetic material that leads to affecting several genes, including those located on different chromosomes.

  • Ex. Crossing over, which recombines genetic material from different chromosomes.
  • Ex. Loss or duplication of portions of chromosomes during DNA replication.
55
Q

Chromosomal mutation vs. Point mutation

A

Point mutations usually only affect one gene, whereas chromosomal mutations can affect several genes.

56
Q

Causes of mutations

A

Spontaneous mutations, mutagens, tracing through mitochondrial DNA.

57
Q

Spontaneous mutations

A

Mutations that are caused by molecular interactions that take place naturally within cells.
- One cause is incorrect base pairing by DNA polymerase during the process of DNA replication.

58
Q

Mutagen

A

Substance or event that increases the rate of mutation in an organism; may be physical or chemical.

59
Q

Physical mutagens

A

Agent that can forcibly break a nucleotide sequence, causing random changes in one or both strands of a DNA molecule.
- Ex. X-rays, gamma rays, UV radiation (UV can cause chemical reactions between C and T bases, which interferes with replication. Can lead to melanoma, form of skin cancer).

60
Q

Chemical mutagens

A

Molecule that can enter the cell nucleus and induce a permanent change in the genetic material of a cell by reacting chemically with DNA.
- Mutagen may act by itself by inserting itself into the DNA molecule to cause nucleotide substitution or frameshift mutation.
- Mutagen can also have a similar structure to ordinary nucleotides but with different base-pairing properties. When these mutagens are incorporated into a DNA strand, they cause incorrect nucleotides to be inserted during DNA replication.
Ex. Nitrites (food preservative), gasoline fumes, compounds in cigarette smoke.
- Most chemical mutagens are carcinogenic.

61
Q

Carcinogenic

A

Cancer-causing, associated with cancers.
- Cancer is the result of somatic cell mutations that disrupt the expression of genes involved with the regulation of the cell cycle.

62
Q

Nuclear DNA vs. Mitochondrial DNA (mtDNA)

A

Nuclear DNA is inherited from all ancestors, mtDNA is only inherited from the maternal lineage.

63
Q

Mitochondrial DNA (mtDNA)

A

DNA within the mitochondria; is genetically identical to that of the female parent because the cytoplasm of offspring is derived from the egg (ovum).

  • Study of mtDNA is being used to gather information about the more recent history of individual species.
  • MtDNA is genetically identical to the mother, because the cytoplasm in a zygote is donated by the ovum. Sperm does not donate any cytoplasmic organelles.
  • If two people have identical mtDNA sequences, they likely share a common and relatively recent maternal ancestor.
64
Q

Endosymbiont theory

A

Proposes that eukaryotic cells arose through a process in which one species of prokaryote was engulfed by another.

  • The different genetic code of mitochondria and chloroplasts supports theory that these organelles were once independent prokaryotic cells.
  • These cellular organelles have their own DNA, and their genome is replicated, transcribe and translated independently from the DNA in the nucleus of the cell they are found.
65
Q

Genetic engineering

A

Manipulation of genetic material to alter genes and blend plant, animal and bacterial DNA

66
Q

Recombinant DNA

A

A molecule of DNA that includes genetic material from different sources. Used by biotechnology
→ An aspect of biotechnology is ability to transfer genes from individuals of one species to another. (Ex. Inserting human genes into bacterial cells, which benefits human medicine.)

67
Q

Biotechnology and insulin

A

We can take gene for human insulin and insert it in a bacterial cell, culture the bacteria (make a colony of bacteria that contain the human gene for insulin), and let the bacteria create human insulin for us.

68
Q

Steps of Recombinant DNA

A
  1. Obtain a human cell(s) from a person who doesn’t have diabetes mellitus and extract the DNA.
  2. Cut human DNA into smaller pieces. We cannot insert the entire human genome into a bacterial cell so we need to cut the DNA into smaller pieces. We will take the fragment containing the gene for insulin and insert into the bacteria. To cut DNA, you need to use restriction enzymes.
  3. Once you have cut the DNA into smaller pieces, you need to isolate the piece that has the insulin gene by using gel electrophoresis. (Electrophoresis is a way to separate DNA fragments based on their differing sizes.)
  4. Now the gene for insulin is isolated, you insert it into a plasmid vector. (A plasmid vector is what we use to give the gene “a lift” into the bacterial cells.)
  5. Once you have the gene in a plasmid, you can put the plasmid into a bacterial cell. Then, you culture the bacteria to get a whole colony of insulin producing bacteria.
69
Q

Describe inserting genes into plasmids

A

A bacterial cell has no nucleus so its chromosomal DNA is located in the cytoplasm. The bacteria might contain plasmids also, which are small circular pieces of DNA found in the cytoplasm that contains genes that are also expressed. Plasmids are very easy to transfer between cells. We are trying to insert the gene into a plasmid, then we could put the plasmid into the bacterial cell.
To insert the gene into the plasmid, we have to make a cut in the plasmid so we can insert the gene in. We use restriction enzymes (the same restriction enzymes used to cut the human DNA). Then, we glue the gene in place by using enzyme DNA ligase.

70
Q

Restriction enzymes

A

Enzymes in prokaryotes that catalyzes the cleavage of DNA at a specific nucleotide sequences.

71
Q

Gel electrophoresis

A

Tool used to separate molecules according to their mass and charge; can be used to separate fragments of DNA.

72
Q

Plasmid

A

Small self-duplication loop of DNA in a prokaryotic cell that is separate from the main chromosome and contains from one to a few genes

73
Q

DNA ligase (recombinant)

A

Enzyme that splices together sticky ends that have been cut by a restriction endonuclease; catalyzes the formation of phosphate bonds between nucleotides.

74
Q

Restriction endonuclease

A

Type of restriction enzyme that recognizes a specific short sequence of nucleotides (target sequence) within, rather than at the ends of, a strand of DNA and cuts the strand at that particular point within the sequence (restriction site)

75
Q

Process of gel electrophoresis

A
  1. Solution that contains DNA fragments is applied to one end of a gel
  2. Electric current is then passed through the gel which causes one end of the gel to develop a positive electric charge and the other end to develop a negative charge.
  3. Because DNA has negative charge, the DNA fragments tend to move toward the gel’s positive end. The smaller fragments move more quickly.
  4. After a period of time, the fragments separate into a pattern of bands. The pattern is called a DNA fingerprint.
76
Q

DNA fingerprint

A

The pattern of bands into which DNA fragments sort during gel electrophoresis.

77
Q

Biotechnology and transgenic organisms

A

→ Biotechnology produces transgenic organisms.
- Transgenic: Genetically engineered; a transgenic organism is produced by incorporating DNA from one organism into another to create a new genetic combination.

78
Q

Biotechnology and medicinal bacteria examples

A
  • Human insulin synthesized by transgenic bacteria to make medicines at a lower cost.
  • Genetic engineering created bacteria that naturally clean up soils polluted with PCBs (polychlorinated biphenyls). AKA bioremediation.
  • Bioremediation: Use of living cells to perform environmental clean-up tasks.
    Ex. bacteria to clean up PCBs, bacteria to clean up oil spills, filter air, remove metals from water.
79
Q

Biotechnology and transgenic plants

A
  • Genetically modified plants can increase resistance to herbicides, insect pests, or viruses.
  • Made possible for plants to grow in new places (whether in drought or colder climates)
  • Genetically engineered plants to create healthier foods with more nutritional value.
80
Q

Biotechnology and cloned and transgenic animals

A

Clones: One pair of organisms (or more) that are genetically identical.
- Genetically engineer animals with useful traits.
Ex. Transgenic milk-producing animals, such as goats, are being used to produce pharmaceutical products.
- Developing transgenic animals that can serve as organ donors for humans.
Ex. Animals usually can’t donate organs to humans as antigens produced by the animal cells cause a serious immune response.

81
Q

Ultrasound

A

Sound with a frequency greater than the upper limit of human hearing, used in a procedure by which sounds waves sent through the body provide information about internal structures, such as a developing fetus.
- The sound waves bounce off the developing fetus and are used to create a cross-sectional image of the fetus. This image can produce abnormalities.

82
Q

Amniocentesis

A

Procedure by which a needle is used to withdraw a small sample of amniotic fluid from the uterus in order to perform a genetic analysis for safety, cannot be performed before the 14th week of pregnancy.

83
Q

Chorionic villi sampling

A

Procedure where fetal cells are removed from the chorion (a tissue that surrounds the amniotic sac and makes up the fetal placenta) to perform genetic analysis; can be performed around the 9th week of pregnancy.

84
Q

Genetic markers

A

A characteristic that provides information about the genotype of an individual.

85
Q

DNA probe

A

Molecule of DNA with nucleic acid sequence that is labelled with a radioactive or fluorescent chemical tag; binds to a complementary DNA sequence and can be used to locate a specific genetic marker.

86
Q

Explain process of using a DNA probe to test for certain genetic markers

A
  1. Genetic material from a fetal tissue sample - or a child or adult - can also be screened for specific genetic markers.
  2. Genetic markers are found using a DNA probe.
  3. DNA from the tissue sample is placed in a suspension with the DNA probe. If the DNa sample contains the gvene of interest, the probe will bind to the marker sequence.
  4. Using the tag, researchers can verify the presence of the gene of interest.
87
Q

Gene therapy

A

The process of changing the function of genes to treat or prevent genetic disorders.
- Results of gene therapy trials show that some disorders, such as diabetes, can be combated by targeting their genetic causes, rather than simply treating their symptoms.
→ In gene therapy, a molecule called a DNA vector carries foreign DNA into target cells in the patient

88
Q

DNA vector

A

In gene therapy, something (commonly, a modified form of virus) that carries recombinant DNA containing a desired gene into a host cell in order to incorporate the gene into a patient’s genome.
- Viruses are well-suited to gene therapy because most have the ability to target certain types of living cells and to insert their DNA into the genomes of these cells.

89
Q

Process of gene therapy

A
  1. The intact virus is made up of a protein coat containing a strand of DNA.
  2. The viral DNA is isolated and the disease-carrying portion of the viral genome is spliced out. Genes coding for the enzymes allow the virus to insert its DNA into the genome of its host cell that are left intact.
  3. A working human genes inserted into the viral genome. The modified viruses are then cultured with human cells. Some of the viruses will transfer the new gene into the cells’ gamete.
90
Q

Somatic gene therapy

A

Therapy aimed to correcting genetic disorders in somatic cells. It improved the health of the patient, but does not prevent the disorder from being passed onto the patient’s children.

91
Q

Germ line therapy

A

Gene therapy used to modify the genetic information carried in egg and sperm cells. This kind of therapy could eliminate inherited genetic disorders, but has unforeseen effects on future generations.

Biology 30 (7 decks)

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