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Bio 1 > Test 2 study guide > Flashcards

Test 2 study guide Flashcards

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Biology 101 flashcards
1
Q

How can we recognize incomplete dominance?

A

With the apparition of a new phenotype in F2

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2
Q

What are the ratios of incomplete dominance in F1 and in F2?

A

F1: 100%
F2: 1:2:1

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3
Q

Where does the pigment of a flower or hair comes from?

A

A protein has to be coded for it

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4
Q

What is codominance?

A

When both phenotypes are expressed

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5
Q

What is the main difference between Incomplete dominance and codominance?

A

Codominance does not have the apparition of a new phenotype.

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6
Q

Describe both types of lethal alleles.

A

Lethal recessive alleles: when mop+ is dominant over mop-, leading to mop- homozygous individuals that have never been found
Lethal dominant alleles: H+ is domiannt over H- but the homozygous H- is normal whereas the other are affected.

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7
Q

What are the rations of both recessive and dominant lethal alleles

A

Lethal recessive alleles: 3:0
Lethal dominant alleles: 0:1

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8
Q

Why are lethal dominant alleles rare?

A

They are rare because they often result in the death of an organism before it can transmit its lethal allele on its offspring.

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9
Q

What is epistasis?

A

Circumstance in which the expression of one gene is affected by the expression of one or more independently inherited genes

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10
Q

What ratio is found in epistasis in the F2 generation?

A

9:3:4

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11
Q

What are multiple alleles?

A

A small difference in the DNA sequence of a gene at one or more points, which results in detectable differences in the structure of the protein.

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12
Q

What is polygenetic inheritance?

A

When traits are conferred by multiple genes, known as quantitative traits, in the numerical realm (continuous range of variation)

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13
Q

What could be examples of a polygenic inheritance

A

hair color, eye color, skin

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13
Q

Are sex-linked genes inherited the same in males and females?

A

No

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13
Q

What is SRY

A

This stands for the sex-determining region, carried on the Y chormosome

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14
Q

How are called genes located on the sex chromosomes?

A

sex-linked genes

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15
Q

True or False: For the first month of embryonic development, reproductive organs and tissues are the same for XX and XY embryos.

A

True

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16
Q

After how much time does the SRY gene become active?

A

After 6 to 8 weeks

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17
Q

What is the function of the SRY gene?

A

It produces a protein that regulates the expression of other genes, stimulating part of these structures to develop testes

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18
Q

Where are coded the genes governing structures needed by only one sex such as breast development, penis strcuture…?

A

They are coded on autosomes

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19
Q

The human X chromosome codes for which phenotype needed by both sexes?

A

Color perception, Blood clotting, DNA replication

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20
Q

Where were the first sex-linked genes first discovered?

A

They were discovered in Drosophila flies

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21
Q

What does a + and a - mean in genes?

A

A + means that the gene is functional and - means that the gene is not functional

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22
Q

Describe the 4 possible inheritance pattern

A

Autosomal recessive: The allele for the trait is recessive and carried on a autosome
Autosomal dominant: The allele for the trait is dominant and carried on an autosome
X-linked recessive: The allele for the trait is recessive and is carried on the X chromosome
X-linked dominant: The allele for the trait is dominant and is carried on the X chromosome

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23
Q

How can you deduce information about pedigrees?

A

If it skips a generation: probably recessive
If all affected females have affected sons: X-linked recessive
If all affected males have affected daughters: X-linked dominant
If tendency (all boys are affected or all girls or mostly boys or mostly girls) then probably x-linked

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24
Q

What consist the process of transcription?

A

The process of converting DNA to RNA

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25
Q

What is the process of translation?

A

The process of converting RNA to protein

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25
Q

What is the DNA template strand?

A

The template strand reads from 3’ to 5’ TAC

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26
Q

What are the different stop codons?

A

DNA: ATT, ATC, ACT
RNA: UAA, UGA, UAG

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27
Q

What allows the process of translation?

A

ribosome

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28
Q

What is the difference between prokaryotes and eukaryotes process of translation?

A

Prokaryotes: mRNA is immedietly ready for translation
Eukaryotes: Pre-mRNA has to be processed in order to allow translation

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29
Q

In what way is mRNA oriented?

A

Always 5’ to 3’

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30
Q

How are called a triplet in gene expression?

A

A codon

31
Q

With what starts every protein?

A

Methionine

32
Q

In DNA, what are the complementary base pairs? and in RNA?

A

DNA: C-G, A-T
RNA: G-C, U-A

33
Q

True or false, The 5’ to 3’ RNA sequence matches the 5’ to 3’ of the DNA coding strand.

A

True

34
Q

What are the characteristics of a somatic mutation?

A

It occurs in nongermline tissues and cannot be inherited

35
Q

What are the characteristics of germline mutations?

A

They are present in egg or sperm, they can be inherited, and they cause cancer family syndrome

36
Q

What does SNP stand for? How many genes does it typically affect?

A

Single nucleotide polymorphism which is a change in the shape. It can impact more than one gene but it typically only affects one gene.

37
Q

In what consist missense mutations?

A

It alters the identity of one amino acid, does not change the reading frame, and has moderate to serious effect on the protein

38
Q

In what consists nonsense mutations?

A

It generates an early stop codon, the protein is being truncated, and it has severe effects on the function of the protein

39
Q

In what consists silent mutations?

A

It generates no change, the protein remains identical, and genreally it has no effect on the protein.

40
Q

What are the three types of base substitution?

A
  1. missense mutation
  2. nonsense mutation
  3. silent mutation
41
Q

What are the two types of SNP?

A
  1. base substitution
  2. Frameshift mutations
42
Q

In what consist frameshift mutation?

A

It is an insertion or deletion that will change the reading frame, the remainder of the protein is changed, and eventually a premature stop codon will end transmission

43
Q

What are the four types of large chromosomal rearrangements (LCR)

A
  1. deletion
  2. duplication
  3. translocation
  4. inversion
44
Q

Give an example of deletion

A

The deletion of chromosome 5 typically leads to severe cognitive impairment and a malformed larynx (cri-du-chat disorder)

45
Q

Give an example of duplication

A

Mammals have genes that encode several types of hemoglobin that are not present in vertebrates such as sharks that evolved earlier. The hemmoglobin found in mammals appeared through duplications, followed by mutations.

46
Q

Give an example of translocation

A

A particular cancer of the human immune system, Burkitt lymphoma is caused by a translocation that moves a segment of human chromosome 8 to the end of chromosome 14

47
Q

When can translocation occur? and what is it?

A

When a segment breaks from one chromosome and attaches to another, non-homologous chromosome, it can happen in mitosis

48
Q

Give an example of Inversion

A

5 chromosome pairs of humans show evidence of translocation and inverse that were not present in our ancestors

49
Q

When does deletion occur?

A

It occurs if a broken segment is lost from a chromosome

50
Q

When does duplication occur?

A

It occurs if a segment is broken from one chromosome and inserted into its homologous. In the homologous chromosome, the alleles inserted are added to those already there.

51
Q

When does inversion occur?

A

When a broken segment reattaches to the same chromosome from which it was lost but in reverse order.

52
Q

What is the difference or similarity between LCR and SNP

A

LCR are rearrangments of chromosmes where it can impact several genes while SNP are mutations that typically imapct a single gene.

53
Q

What are the three steps of transcription and explain them?

A
  1. initiation: Transcription factors bind to the promoter and together recruit RNA polymerase
  2. Elongation: the newly synthesized pre-mRNA molecule is elongated by adding new RNA bases to the RNA strand in the 5’ to 3’ direction
  3. Termination: Once the synthesisof the pre-mRNA is completed, the RNA polymerase is released
54
Q

What is the transcription factors?

A

It is proteins that binds to DNA to regulate the expressions of genes by promoting or suppressing transcription

55
Q

What is the transcription unit?

A

It is the open reading frame

56
Q

What is the function of the promoter?

A

It recruits the necessary proteins to initiate transcription

57
Q

What is the promoter made of?

A

It is made of DNA sequence like TATA box on which transcription factors will bind. It is present in archaea and bacteria.

58
Q

Explain the initiation process of transcritption.

A

Each gene contains a promoter that contains DNA sequences such as TATA box on which transcription factors will bind. The transcrption factors are proteins with an active site able to bind DNA sequences and then recruit the RNA polymerase. Once the RNA polymerase binds to the DNA sequence, the transcription begins.

59
Q

Explain the elongation process of transcription.

A

DNA is unwound while new complementary RNA bases are added to the newly formed RNA strand. A DNA-RNA dimer briefly exists after transcription and then DNA rapidly rewinds into a double stranded molecule

60
Q

Which RNA polymerase is needed for the process of elongation in transcription?

A

RNA polymerase II

61
Q

Explain the termination step in transcription.

A

RNA polymerase is released. In eukaryotes, we now have pre-mRNA, it still has to be processed into a translatable mRNA

62
Q

What are the three types of RNA polymerase and their function?

A
  1. RNA polymerase I: it is used to transcribe DNA into rRNA (generates ribosomes)
  2. RNA polymerase II: It is the enzyme used to transcribe protein coding genes (mRNA)
  3. RNA polymerase III: It is the enzyme used to transcribe DNA into tRNA and some parts of rRNA.
63
Q

What does tRNA stand for?

A

It stands for transfering the amino acids to the ribosomes to build the polypeptitde during translation

64
Q

Describe and explain the initiation of translation.

A

A specialized methionine bound to a GPT is used as an initiator of translation, the ribosome scans the mRNA until it reaches the start codon, establishing the correct reading frame

65
Q

What is the role of the ribosome?

A

To facilitate the interactions between the tRNA and the mRNA molecule and to hold the growing chain of amino acids

66
Q

Describe and explain each step of the elongation process of translation.

A

This time, elongation uses amino acids instead of nucleotides. The peptidyl transferase (enzyme that catalyzes formation of a bond) cleaves the amino acid from the tRNA in the P site and forms a peptide bond in the A site. Once the amino acid transfer is complete, the ribosome translocates along the mRNA molecule and the polypeptide chain is attached on the most recent amino acid. Once the translocation is done, the empty tRNA in the E site is released and the A site is now free to receive the next tRNA corresponding to the next codon.

67
Q

What is slower, DNA replication, RNA transcription or protein sythesis?

A

Protein synthesis

68
Q

Explain and describe the terminationin translation

A

Termination uses a release factor

69
Q

What is the function of a chaperon?

A

They are proteins that assist in the folding or assembly of other proteins

70
Q

What is an operon?

A

A sequence of genes plus a promoter and an operator that are involved in the same metabolic pathway.

71
Q

What is the function of lacZ, betagalactosidase?

A

It converts lactose into allolactose and facilitates the cleaving of lactose into galactose and glucose

72
Q

What is the function of lacY, permease?

A

It makes the cell membrane permeable to lactose.

73
Q

What is catabolism and what operons does it use?

A

It is the ensemble of reactions that lead to the degradation of molecules, it produces energy. It occurs in lac operons.

74
Q

What is anabolism and wich operons does it use?

A

It is the ensemble of reaction that lead to the construction of molecules. It consumes energy. It occurs in trp operons

75
Q

What is the difference between lac operons and trp operons?

A

lac operons are activated when there is lactose whereas trp operons are activated when there is no tryptophan.

76
Q

What are the two possibilities for a lac operon?

A
  1. lactose is absent: repressor is active binds to the operator so no transcription occurs
  2. Lactose is present: lactose converts to allolactose that inactivates the repressor preventing it to bind to the operator allowing transcription.
77
Q

What are the two possibilities for a trp operon?

A
  1. trp absent: the repressor is inactive preventing it to bind to the operator, allowing transcription
  2. trp present: the repressor is inactive and gets activated by tryptophan that allows to bind to the operator blocking transcription.
78
Q

Which operons are repressible and which are inducible?

A

Lac operons: inducible
Trp operons: repressible

Both illustrate negative gene regulation because both are regulated by a repressor that turns off gene expression when it binds DNA

79
Q
A

Bio 1 (2 decks)

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