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Bio > exam #3 > Flashcards

exam #3 Flashcards

1
Q

Describe the origin and function of DNA.

A
  • Passed from parents to offspring
  • Serves as the instruction manual for how to build and individual
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2
Q

Describe the location of DNA in eukaryotic cells

A
  • Found in the nucleus
  • In the form of a chromosome
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3
Q

Describe the structure of chromosomes

A

Single DNA molecule wrapped around proteins

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4
Q

Describe the number and origin of the chromosomes in human cells

A
  • 23 pairs of chromosomes (46 chromosomes in total)
  • One chromosome from each pair is inherited from the biological mother, and the other from the father
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5
Q

Identify the 4 types of DNA nucleotides and their basic structure

A
  • Adenine
  • Thymine
  • Guanine
  • Cytosine
  • Phosphate, sugar, and base
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6
Q

Which two parts of the nucleotides form the DNA backbone?

A

Sugars and phosphates

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7
Q

Explain how nucleotides are linked together to form individual DNA strands.

A

Held together by covalent bonds between the 5’ phosphate group and 3’ -OH group

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8
Q

Explain how two DNA strands are bonded together to form a double helix.

A

Held together by hydrogen bonds between the bases of each strand

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9
Q

Understand and describe which feature of DNA varies among individuals, making each of us unique.

A
  • Specific sequence of nucleotides along a strand of DNA is unique to each individual
  • The order of the bases determines individual characteristics
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10
Q

What is the nucleotide base pairing rule?

A
  • A always pairs with T
  • C always pairs with G
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11
Q

Why must DNA replicate in living cells

A

For growth, repair, and regeneration of tissues

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12
Q

Describe the steps in DNA replication

A
  • Separating strands – hydrogen bonds are broken and the helicase enzyme unwinds DNA
  • Adding nucleotides – DNA polymerase reads DNA and adds complementary nucleotides
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13
Q

The role of enzymes; helicase and DNA polymerase

A
  • Helicase: break hydrogen bonds and unwind DNA
  • DNA polymerase – reads DNA and adds complementary nucleotides
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14
Q

What is semiconservative method?

A
  • DNA replication produces two copies of the original DNA molecules
  • Each molecule consists of one of the strands of the original DNA molecule and a new strand
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15
Q

Why is PCR used?

A

To amplify (replicate) a specific DNA segment to study it

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16
Q

Describe the steps of PCR

A
  • Put DNA, free nucleotides, polymerase enzyme, and primers into a tube
  • Heat and cool to allow strands to separate and pair with new nucleotides
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17
Q

What ‘ingredients’ are used in PCR

A
  • DNA
  • A, T, C, G
  • DNA polymerase
  • primers
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18
Q

Compare and contrast PCR to natural replication

A
  • Natural replication happens naturally
  • PCR happens in a tube
  • PCR can make billions of copies with just a sample of DNA
  • Natural replication only makes two new DNA strands at a time
  • Both make copies of DNA
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19
Q

What is DNA profiling?

A
  • Visual representation of a person’s unique DNA sequence
  • Allows us to identify the unique characteristics in the DNA of a person
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20
Q

What is a genome?

A

Complete set of genetic instructions encoded in all the chromosomes of an organism

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21
Q

Explain what are STR (short tandem repeats)?

A

Sections of a chromosome in which short DNA sequences are repeated

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22
Q

Explain how PCR and gel electrophoresis are used to create a DNA profile?

A
  • PCR is used to amplify the STR regions
  • Gel electrophoresis is used to separate the STRs
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23
Q

Given a picture of a gel, be able to distinguish similarities and differences in individuals.

A

Smaller fragments travel farther in the gel than larger fragments

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24
Q

How many STRs should be analyzed to generate a unique DNA?

A

At least 15 STR regions

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25
Q

What does PCR stand for?

A

polymerase chain reaction

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26
Q

define proteins

A

Macromolecule made of repeating amino acid subunits

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27
Q

define genes

A

A sequence of DNA that contains the instructions to make one or more proteins

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28
Q

define gene expressions

A

the process of converting information from the coding sequence of a gene into a protein

29
Q

define alleles

A

different forms of a gene

30
Q

Describe the structural similarities and differences among amino acids.

A
  • Similar: use the same nucleotides (A,G,C,U)
  • Difference: functions and codons
31
Q

Explain how a protein achieves its final 3-dimensional shape.

A

the chain on amino acids folds to protect the hydrophobic amino acids from the aqueous environment of the cell

32
Q

Describe the relationship between a protein’s 3-dimensional shape and its function.

A

The shape of the protein is specified by its specific amino acid sequence

33
Q

Explain the relationships among proteins, DNA, genes, and chromosomes.

A

Chromosome have many genes along their length. Each gene contain instructions to make at least one protein. Depending on the needs of the cell at any given time, each gene may be expressed or silenced

34
Q

Explain how differences in DNA sequence can result in different protein shapes.

A

the sequence of amino acids in the chain and how the side chains of those amino acids interact with each other

35
Q

Explain gene structure and function in terms of regulatory and coding sequences.

A
  • Regulatory sequences are at the beginning of the gene and make sure the gene is activated at the correct time
  • Coding sequences are the specific amino acids that will result in the protein
36
Q

Transcription in detail

A
  • Converts DNA to RNA
  • Occurs in the nucleus
  • Molecules of mRNA are synthesized from the genes
  • RNA binds the regulatory sequence of the genes coding regions
  • RNA polymerase copies a strand of DNA into a strand of mRNA
  • mRNA stand is formed and detaches from the DNA sequence
  • DNA reforms
  • The mRNA leaves the nucleus
  • DNA is unchanged and stays in the nucleus
37
Q

Translation in detail

A
  • Converts RNA to protein
  • Occurs on ribosomes in cytoplasm
  • Ribosome moves along mRNA readings the codons
  • tRNA carries an amino acid to the mRNA and ribosome by using its anticodon to find a matching mRNA codon
  • ribosome moves onto next codon after tRNA places the specified amino acid
  • the completed amino acid chain detaches from the ribosome and folds into its 3D shape
38
Q

What are coding regions?
What are Noncoding regions?

A
  • Coding region: part of the gene that is used as a template to produce RNA molecules in transcription
  • Noncoding regions: portions of an organisms genome that do not code for amino acids
39
Q

Describe the role of mRNA, in these two processes.

A
  • In transcription, mRNA is being created
  • In translation, mRNA is being read and a chain of amino acids is being created off of it
40
Q

Define the terms “codon” and “anticodon”.

A
  • Codon: groups of 3 nucleotides in a DNA/RNA molecule
  • Anticodon: group of 3 nucleotides in a tRNA molecule
41
Q

How can organisms be genetically modified to produce recombinant proteins?

A

Combine a regulatory sequence with a coding sequence

42
Q

Explain how a recombinant gene is created.

A

It contains parts of different genes that aren’t found together in nature

43
Q

Explain how to produce a transgenic organism using a recombinant gene.

A

Insert the recombinant gene into living cells

44
Q

Explain the statement “the genetic code is universal” and its significance for developing and using transgenic organisms.

A
  • Nearly every species reads the code the same exact way
  • 64 possible codons code for 20 different amino acids
45
Q

What are genetically modified organisms?

A

Organisms that have received recombinant genes

46
Q

What are the pros and cons of making genetically modified organisms?

A
  • Pros: herbicide-resistant crops, insulin produced by bacteria, genetically modified spider silk
  • Cons: who regulates GMOs, how far will it go, ethical concerns
47
Q

Define gene therapy

A
  • Influencing genes to reduce or eliminate the effects of a genetic disorder
  • An altered virus inserts healthy versions of the gene into the genome of patients
48
Q

Define mutation

A

Changes in DNA sequence

49
Q

Explain mutation’s role in evolution

A
  • Mutations that occur in germ cells can be passed onto the next generation
  • Mutations produce variations
  • Without mutations, there would be no evolution
50
Q

What causes mutations

A

Errors in DNA replication

51
Q

Describe the various types of mutations and their effects

A
  • Point mutation: substituting one nucleotide for another
  • Frameshift mutation: change in the reading frame of a gene
  • Rearranged DNA mutation: section of DNA moves
52
Q

Point mutation:

A

i. Silent - change one nucleotide to another; no change in amino acid sequence
ii. Missense - change one nucleotide to another; different amino acid sequence in this location
ii. Nonsense - change one nucleotide; introduces early stop codon

53
Q

Frameshift mutations:

A

I. insertion - insert one or more nucleotides; shifts reading frame of every codon after the insertion
II. deletion - delete one or more nucleotides; shifts reading frame of every codon after the deletion

54
Q

Rearranged Mutations:

A

I. Inversion - group of DNA nucleotides are flipped to read in reverse order; different amino acid sequence in this location
II. Translocation - move segments of DNA from one chromosome to another, fusing portions of different genes together

55
Q

What are mutagens? Examples

A
  • Any chemical/physical agent that can damage DNA by changing the nucleotide sequence
  • X-rays, UV rays
56
Q

Explain the process of gene therapy as a treatment for sickle cell disease.

A
  • Because sickle cell disease is genetically inherited, gene therapy could potentially be used to treat it
  • Viral vector approach: an altered virus insets healthy versions of the gene into the genome of patients
  • Gene switch approach: does not change genes, but simply changes gene expression to help patients produce functional hemoglobin
  • Precise gene editing: CRISPR can be used to inactivate a gene without replacing it with another version
57
Q

Explain how gene therapy can be used to turn on or off genes.

A

Gene therapy can replace a gene that is missing or causing a problem and it can add genes to help the body treat disease

58
Q

Define CRISPR.

A
  • Clustered regularly interspaced short palindromic repeats
  • Acts as molecular scissors, cutting a specific DNA sequence
59
Q

Explain how CRISPR is used to edit DNA including correcting genes or disrupting genes.

A
  • The enzyme contains RNA with a sequence that matches with the target DNA
  • An enzyme cuts DNA at a target sequence
  • The mutated DNA is removed
  • A normal version of the DNA is introduced
  • Repair enzymes insert the normal version of DNA into the chromosome
60
Q

Differentiate between somatic or germ-line cells.

A
  • Germ cells: sperm and egg cells, have the potential to pass genetic information to the next generation
  • Somatic cells: all other body cells, cannot affect the next generation
61
Q

Explain how genetic conditions treated with CRISPR can be passed to a child.

A

CRISPR edits down to the molecular level so the DNA that was edited will be passed down to your child

62
Q

Define sickle cell trait.

A
  • Crescent shaped red blood cells
  • Carry small amounts of oxygen
  • Caused by genetic mutation in the beta-globin gene
63
Q

Explain why sickle cell trait could be favorable.

A

People with 1 copy of sickle cell allele are more resistant to malaria

64
Q

What are stem cells and how are they different from other cells?

A
  • Present in the early embryo
  • They do not have a specific job or function
  • Have the potential to become other cells in the body
65
Q

What are committed cells?

A

Cells that can only become certain types of cells

66
Q

Where do stem cells come from?

A

Bone marrow, amniotic cells, adipose tissue, umbilical cords, and placental tissue (basically everywhere)

67
Q

How do stem cells play a role in regenerative medicine?

A

Using stem cells for medical treatments and research

68
Q

What is the importance and benefits of regenerative medicine?

A

Helps patients heal faster than treatment with conventional methods

69
Q

How can new tissues be produced by regenerative medicine?

A

Stem cells allow the tissue to “self-assemble”

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