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Biology Exam 2 > Biology Exam 3 > Flashcards

Biology Exam 3 Flashcards

1
Q

Alleles

A

Different versions of a gene (purple flower color allele vs. white flower color allele).

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2
Q

Homozygous:

A

2 of the same allele (AA or aa).

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3
Q

Heterozygous

A

1 of each allele (Aa).

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4
Q

Dominant

A

overpowers the recessive allele.

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5
Q

Gene

A

located on chromosomes.

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6
Q

Genotype

A

genetic makeup (DNA, genes). They are alleles.

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7
Q

Phenotype

A

appearance or the expression of traits.

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8
Q

How does a genotype determine a phenotype?

A

Through the production of proteins.

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9
Q

Incomplete dominance

A

The dominant allele is not completely dominant. The heterozygous individual is a blend of both alleles. RR = red. Rr = pink. rr = white. More of a blend.

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10
Q

Codominance

A

Both dominant and recessive traits show up in heterozygotes. Heterozygous individual has both phenotypes, not new. RR = red. Rr = red and white striped or spotted. rr = white. Less of a blend.

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11
Q

What are the phenotypes possible in the ABO blood groups of humans?

A

Type A, Type B, Type AB, Type O.

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12
Q

What are the genotypes possible in the ABO blood groups of humans?

A

AA, AO: A.
BB, BO: B.
AB: AB.
OO: O.

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13
Q

What is a sex-linked gene?

A

Some genes are located on sex chromosomes. Examples: colorblindness, hemophilia.

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14
Q

Compare and contrast the structure of DNA and RNA

A

DNA:
Sugar for DNA is deoxyribose.
Bases: AGTC.
Two strands.

RNA:
Sugar for RNA is ribose.
Bases: AGUC.
One strand.

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15
Q

Describe the process of DNA replication

A

Done before cell division.
DNA replicates in a semi-conservative way. Each parent strand gets a new daughter strand.
The 2 parent strands separate, DNA adds new matching nucleotides to each strand to form new strands.
Occurs in Nucleus

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16
Q

Describe the process of DNA Transcription

A

During this process, the DNA sequence of a gene is copied into RNA.
Before transcription can take place, the DNA double helix must unwind near the gene that is getting transcribed.
Occurs in nucleus

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17
Q

Describe the process of translation

A

Occurs in cytoplasm
the process through which information encoded in messenger RNA (mRNA) directs the addition of amino acids during protein synthesis.

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18
Q

What is the purpose of mRna?

A

messenger RNA has the copy of the gene. Will be read to make protein.

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19
Q

What is the purpose of tRNA?

A

Transfer RNA. Helps make the protein by bringing amino acids.

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20
Q

The purpose of a ribosome

A

Translation (making a protein) is carried out by a ribosome with the help of tRNAs.

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21
Q

The purpose of RNA polymerase

A

to transcribe DNA to RNA.

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22
Q

What is a codon?

A

Code for 1 amino acid.

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23
Q

Know the purpose of DNA Polymerase

A

to accurately and efficiently replicate the genome in order to ensure the maintenance of the genetic information and its faithful transmission through generations.

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24
Q

What are substitution mutations and insertions/deletions?

A

Substitution Mutations: replace one nucleotide with a different one.

Insertions/deletions: One of more nucleotides are inserted/deleted from the gene. Can result in a frameshift.

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25
Q

Silent mutation

A

The resulting amino acid is the same.

26
Q

Missense mutation

A

The resulting amino acid is different.

27
Q

Nonsense mutation

A

results in a stop codon.

28
Q

Know what happens when RNA polymerase binds to the promoter of an operon

A

It transcribes the operon and makes mRNA.

29
Q

Know what happens when a repressor binds to the operator of an operon

A

RNA polymerase is physically blocked by the repressor, so can’t get to the genes. So no RNA made, no transcription.

30
Q

Describe the structure and function of the lac operon

A

RNA polymerase binds to the promoter, so it can do transcription. Lactose binds to the repressor. Repressor is off, meaning the operon is on.

31
Q

Describe the structure and function of the trp operon

A

Operon with genes that produce tryptophan (important amino acid). Can be turned off if too much tryptophan. If a lot of trp, operon is off.

32
Q

What is euchromatin and heterochromatin?

A

Euchromatin is DNA + histones are unwound/open. Genes are turned on.

Heterochromatin is DNA + histones condensed/closed. Genes are turned off.

33
Q

What is epigenetics?

A

Turning genes on and off.

34
Q

How can adding methyl groups to DNA affect gene expression?

A

it can serve as a repressive or activation mark for gene expression.

35
Q

What is X-inactivation? Know that it mostly affects female mammals

A

only one gene copy of the X chromosome is transcriptionally active in individual

36
Q

What are hox genes?

A

a set of transcription factor genes that exhibit an unusual property:

37
Q

What are proto-oncogenes,

A

a group of genes that cause normal cells to become cancerous when they are mutated

38
Q

oncogenes

A

An oncogene is a gene that has the potential to cause cancer.

39
Q

tumor-suppressor genes

A

normal genes that slow down cell division or tell cells to die at the right time

40
Q

What are the two branches of the immune system?

A

Innate and adaptive immunity.

41
Q

Innate immune system: external and internal barriers

A

Innate immune system = we’re born with it. They are defenses that act immediately.

Innate external barriers: Skin, acidic environment, secretions, mucous membranes, cilia.

Innate internal defenses: phagocytic cells, natural killer cells, defensive proteins, inflammatory.

42
Q

Phagocytic cells (macrophages and neutrophils)

A

Phagocytic cell: cell eating, engulfing.

43
Q

Describe the steps of the inflammatory response

A

Bacteria activates macrophages that are in tissue. Sends signals.
Trigger: capillaries dilate & become leaky & increase blood flow..
Neutrophils arrive, leave cappilary, go to infection. Engulf the bacteria.
Platlets form clots to seal the wound.

44
Q

Adaptive immunity: antigens and antibodies

A

Adapts over your lifetime. Has the memory of previous infections.
Responds to antigens: foreign molecules protruding in pathogens.
When antigen is detected: immune system produces antibodies (proteins that bind to antigens. Signal other cells to destroy them.

45
Q

What is the role of the lymphatic system?

A

Battleground during an infection.

46
Q

Two types of lymphocytes: B cells and T cells

A

They’re both white blood cells that live in the limphatic system.
B cells: secrete antibodies into blood.
T cells: Attack the infected cells or anything that has an antibody bound.

47
Q

Explain how B cells respond to an infection

A
  • B cells go through clonal selection.
  • B cell with specific antigen receptor binds to matching antigen on pathogen.
  • This B cell divides into many clones (mitosis).
  • The cloned B cells become: a) plasma cells b) Memory cells

.

48
Q

Two types of B cells: memory cells and plasma cells

A

a) plasma cells: produce & secrete antibodies against that antigen, to mark them for destruction. b) Memory cells: remain in body, activate if antigen returns (for secondary immune response).

49
Q

Live attenuated vaccine -

A

Modified “wild” virus/bacteria can replicate, but weakened so usually do not cause disease (mild if it does).

Usually needs just one dose.

50
Q

Inactivated vaccine:

A

Inactivated (killed) by heat/chemicals. Cannot replicate.
Subunit - pieces of inactivated virus/bac, like just the antigens.

51
Q

Two types of T cells: helper T cells and cytotoxic T cell

A

Helper T cells: activate cytotoxic T cells to kill infected target cells. Cytotoxic cells kill the antigens. Destroys cells marked with antibodies.

52
Q

What is an autoimmune disease and immunodeficiency diseases?

A

Autoimmune disease occurs when the immune system turns aginst the body’s own molecules.

Immunodeficiency diseases are underreactions of the immune system.

53
Q

What is a vaccine and how does it work?

A

Fake virus or bacteria, a harmless version.

54
Q

What is the difference between a vaccine and an antivenom?

A

Vaccines inject antigens, to trigger the production of antibodies and memory B cells.

An antivenom injects antibodies to kill venom.

55
Q

What is herd immunity?

A

A large part of the population is vaccinated or immune. Spread becomes unlikely.

56
Q

How can some viruses cause cancer?

A

Inject their own DNA into your DNA.
Cancer cell with virus puts viral antigens on surface.

57
Q

Know what types of gene expression mammals do

A

DNA packing (going from heterochromatin to euchromatin), X-Inactivation, and RNA interference

58
Q

Know How T cells respond to an infection

A

T cells
- A white blood cell ingests an antigen and displays it on its surface.

  • Helper T cells bind to the displayed antigens on white blood cell and become activated.
  • Activated Helper Tell then activate: plasma B cells to produce antibodies. It will also activate cytotoxic T cells, which are the killer cells, destroys cells marked with antibodies.
59
Q
A
60
Q
A

Biology Exam 2 (5 decks)

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