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Biology 1010 > Genetics Lecture 6 > Flashcards

Genetics Lecture 6 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Example of the 4 eyed fish?

A

Cuatro Ojos “Four Eyes” … the eye’s upper half is
particularly well-suited for areal vision (to watch for predators) and the lower half for aquatic vision (look for food). The cells of the two parts of the eye express a slightly different set of genes involved in vision, even though these two groups of cells are quite similar and contain identical genomes.

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2
Q

Operator

A

A DNA segment that controls the transcription of nearby genes. Found only in prokaryotic genes. A part of the beginning of the gene. it can be turned on and off and be induced.

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3
Q

Structural genes

A

Genes that are back to back and regulated together in prokaryotes. They are different in eukaryotes.

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4
Q

Structure of gene differences between prokaryotes and eukaryotes?

A

Prokaryotes: single, generally circular genome sometimes accompanied by smaller pieces of accessory DNA, like plasmids. Has less bps and everything is mixed together.
Eukaryotes: Genome found in chromosomes, nucleosome structure limits DNA accessibility.

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5
Q

Size of genome differences between prokaryotes and eukaryotes?

A

Prokaryotes: relatively small
Eukaryotes: relatively large

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6
Q

Location of transcription and translation differences between prokaryotes and eukaryotes?

A

Prokaryotes: Coupled, no nucleic envelope barrier because of prokaryotic cell structure. Then can occur at the same time.
Eukaryotes: Nuclear transcription and cytoplasmic translation.

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7
Q

Gene clustering differences between prokaryotes and eukaryotes?

A

Prokaryotes: Operons where genes with similar function are grouped together. They are regulated together to be more efficient.
Eukaryotes: Operons generally not found. Each gene has its own promoter and enhancer elements.

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8
Q

Polysome (polyribosome)

A

When many ribosomes are back to back during translation if the conditions are right. Happens in both organisms.

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9
Q

The direction that prokaryotes are read?

A

Downstream

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10
Q

E.coli

A

It’s found the gut and is good for digestion. Lactose molecules are in it.

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11
Q

Lactose

A

A sugar found in milk and milk products. It turns on the thing that digests it. It has two subunits: galactose and glucose. They are linked by a beta glycosidic bond. The bond will break when you need energy.

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12
Q

LacY

A

Allows the lactose to come in when it senses it outside.

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13
Q

LacZ

A

Encodes an enzyme that breaks apart the bond in lactose.

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14
Q

Glucose

A

What the bacterium uses as a source of energy.

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15
Q

What happens when there is a lot of glucose around and no lactose?

A

The cell doesn’t need to make all the genes necessary to digest lactose, because you don’t need to produce genes you don’t’ need.

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16
Q

What happens when you have lactose around?

A

The lactose itself will turn on the gene (operon) that’s necessary to digest lactose.

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17
Q

What happens in the Induction of β-Galactosidase Synthesis by Lactose in E. coli?

A

The concentration of the lactose metabolizing enzyme increases incredibly.

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18
Q

What are the structural genes in the lactose operon?

A

The enzymes that digest it.

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19
Q

Two types of genes?

A

Structural and regulatory.

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20
Q

What’s the regulatory gene in the lactose operon?

A

LacI

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21
Q

Lactose Repressor

A

LacI is always making a little bit of mRNA so it’s not really regulated. The gene makes mRNA which makes the protein which is an active repressor. When lactose is absent the repressor is active and operon is off. The represser is in the operator, so the RNA polymerase is blocked and nothing happens.

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22
Q

Regulatory Genes Code for what?

A

Regulatory Proteins

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23
Q

Regulatory Proteins

A

Undergo a conformational change (shape change) upon binding a small molecule (ligand) that decreases or increases the protein’s affinity (binding) for DNA.
Regulatory proteins are examples of allosteric proteins because they have two sites: a regulatory site and an active site.

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24
Q

What happens when LacI repressor protein has something binded to its regulatory site?

A

The LacI repressor protein (a regulatory protein)
is inactivated when it binds allolactose (a ligand). This turns on the gene and off the LacI. This is because the protein’s shape changes and it can no longer bind to DNA.

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25
Q

Polygenetic mRNA

A

mRNA with multiple genes back to back.

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26
Q

When are polypeptides called proteins?

A

After they have folded.

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27
Q

What’s the inducible system and inducer with lactose?

A

The lactic acid operon is the inducible system. Lactose is the inducer.

28
Q

Induction of Enzyme Synthesis?

A

Lactose added

29
Q

Repression of Enzyme Synthesis?

A

Tryptophan added

30
Q

Tryptophan

A

An amino acid important for making proteins to allow bacteria to live.

31
Q

Tryptophan’s regulatory gene?

A

trpR, and it makes an inactive repressor. When the Tryptophan is absent, repressor is inactive, operon is on.

32
Q

What does the Tryptophan operon produce?

A

Multiple polypeptide subunits that assemble tomake up enzymes for Tryptophan synthesis.

33
Q

What happens when the Tryptophan is added to the regulatory protein?

A

It turns it to active repressor and blocks the RNA polymerase.

34
Q

What is the Tryptophan cycle?

A

A negative feedback loop, where the thing you are producing the thing that regulates it.

35
Q

Differences between tryptophan and lactose systems?

A

Lactose is where the ligand gets turned off, while in tryptophan the ligand gets turned on.

36
Q

Mutations

A

A Permanent Change in the Hereditary Material, DNA

37
Q

Types of mutations?

A

Chromosomal translocation, Transposition of genes, Point mutations.

38
Q

Chromosomal translocation

A

Occurs when a chromosome breaks and the (typically two) fragmented pieces re-attach to different chromosomes. Has very severe consequences. Eg. Trisomy 21 where chromosome 21 move to chromosome 14.

39
Q

Transposition of genes

A

DNA has junk DNA that has a lot of repeated and genes that don’t need to be used anyone like old diseases. These genes they aren’t used are dormant but sometimes they can get turned on. Then a lot pf genes in the junk gene cut out the enzymes that cut out pieces DNA from the genome, this allows it to get inserted somewheres else. This is called transposable elements/transposons.

40
Q

Point mutations

A

Occur at specific places in a gene

41
Q

Mutagens

A

Physical and Chemical Agents that Promote Mutations.

42
Q

Types of mutagens?

A

Ionizing radiation, Ultraviolet radiation, (these two are physical), Chemical mutagens (this is chemical).

43
Q

Ionizing radiation

A

Different rays like gamma, alpha, beta. They can break both strand of DNA, which sometimes it gets repaired properly, but often it does not.

44
Q

Ultraviolet radiation

A

Rays from the sun, that cause any two t bases next to each other to break the hydrogen bond and instead covalently bond together. This creates a kink in the backbone of DNA. When the shape is different the polymerase can’t read and translate it and it can’t be replicated.

45
Q

How to correct damaged DNA from UV?

A

First, nuclease looks for thymes and removes the DNA. Then the DNA polymerase fills the DNA with the right one. Then DNA ligase zips it back up.

46
Q

Why can’t we have too much sun?

A

Because it will overwhelm this system.

47
Q

Chemical mutagens

A

Chemicals that can be incorporated into DNA; they look similar to DNA nucleotides but promote incorrect base pairing. Chemicals that add or remove groups from nucleotide bases causing incorrect base pairing.

48
Q

Chemical mutagens results?

A

A Base-Pair Substitution (or point mutation) is
introduced during replication of DNA.

49
Q

What happens if you don’t have DNA replication and you are exposed to a mutation?

A

It’s not really a problem.

50
Q

How many hydrogen bonds in A to T?

A

2

51
Q

How many hydrogen bonds in C to G?

A

3

52
Q

5-Bromouracil

A

Can behave as a T or C, but has a Bromine on it. t is a well-known mutagen, causing mutations by mispairing with guanine (G) rather than pairing with adenine (A) during replication.

53
Q

Nucleotide-pair substitution

A

Where the bp is replaced with a different one

54
Q

Silent

A

Can cause NO change in the Phenotype in the protein. Since the codon table is degenerate it can still encode for the same amino acid. This typically occur in the third bp in a codon.

55
Q

Missense

A

Where just one amino acid is different. It can be bad depending on how big the change is. Different categories of animo acids changes function, because of their different structures.

56
Q

What do you need for an enzyme to work?

A

The orientation needs to be the same. If an amino acid changes and it was important to the orientation of a reagent then major problems could occur.

57
Q

An example of missense mutations?

A

Sickle Cell Anemia. It isn’t able to carry oxygen and the proteins clump together.

58
Q

Nonsense

A

Where is creates a stop codon when it shouldn’t. This causes the release factor and the ribosome is blocked and it can’t read the next ones.

59
Q

Nucleotide-pair insertion or deletion

A

Where nucleotides are added or removed.

60
Q

Frameshift (immediate nonsense)

A

Where a nucleotide is added or deleted which creates a stop codon. The sequence gets shifted. It’s immediate because the stop codon immediately comes where we have introduced a mutation.

61
Q

Frameshift (extensive missense)

A

An insertion or deletion of a nucleotide. It’s extensive because all codon will be out of place and incorrect.

62
Q

3 nucleotide pair deletion or insertion

A

Where exactly 3 are added or deleted. It’s not a frameshift because it won’t cause the frame to shift, and the rest of the codons will be the same.

63
Q

p53 protein

A

It’s tutor suppressor and protects against mutations. It happens in the G1 cycle of the cell. It scans the DNA for mistakes and repairs them. It stops the cycle cell as it repairs them. It’s encoded by DNA, and many cancer patients have mutations in these genes.

64
Q

Apoptosis

A

If there is too many errors and it can’t fix them all, p53 will trigger the cell to self-destruct. Then it replicate the erred DNA.

65
Q

Is the cancer causing mutation more likely to be recessive or dominant mutation?

A

Recessive because we have two homologous chromosomes and for every gene we have two alleles, and chances are we have two non-working ones is low.

Biology 1010 (9 decks)

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