Genetics: DNA, RNA, and proteins Flashcards

1
Q

Each chromosome is long, but the DNA is wrapped around proteins that make them

A

shorter

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2
Q

What is the key to distinguish between transcription and translation in gene expression?

A

DNA and RNA are both nucleotide, so they have the same language (transcription)
When you move from RNA to amino acids, you need to translate it

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3
Q

When DNA is transcribed into RNA, thymine is replaced into what base?

A

Uracil

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4
Q

Why do triplets of RNA code each amino acid rather than twins?

A

There are 21 amino acids in total. Twins would only result in 4^2 = 16 combinations. Triplets allow for expression of each amino acid.

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5
Q

What could a base pair switch mutation cause in terms of protein production?

A

A protein codon could turn into a stop codon. making an incomplete protein that doesn’t work

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6
Q

Only around __% of the DNA in our chromosomes codes for a gene

A

3

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7
Q

What are introns? (intragenetic region)

A

Parts of the DNA that are not part of mRNA.

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8
Q

What are exons? (expressed region)

A

Any part of the gene that will encode

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9
Q

Where does DNA to RNA transcription occur?

A

In the nucleus, as you’re not gonna take the chromosome out of it

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10
Q

Hemophilia is an _-linked _________ disorder

A

X, recessive

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11
Q

What is a sex-linked gene?

A

Any gene located on a sex chromosome

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12
Q

What affliction is a common human sex-linked disorder caused by a malfunction of light-sensitive cells in the eyes?

A

Red-green colourblindness

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13
Q

What false conclusion did the scientific community accept for 33 years?

A

That humans have 48 chromosomes. We now know that there are 46.

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14
Q

What is gene mapping?

A

Using methods to identify they locus of a gene and the distances between genes

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15
Q

What is a genetic map and what is a physical map?

A

Genetic maps are based on genetic linkage (recombination) information)
Physical maps use actual physical distances measured in DNA base pairs

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16
Q

What are gene maps used for?

A

Many reasons, including identifying a gene that is responsible fora particular trait or disease

17
Q

Which chromosome is the CF gene found on? How was it found?

A

Chromosome 7

Scientists compared DNA sequences in normal persons and individuals with CF

18
Q

What is nondisjunction? What are the 3 forms?

A

The failure of homologous chromosomes or sister chromatids to separate properly during cell division or meiosis, resulting in the wrong number of chromosomes in daughter cells/gametes

  • Failure to separate a pair of homologous chromosomes in meiosis 1
  • Failure to separate sister chromatids during meiosis 2
  • Failure to separate sister chromatids during mitosus
19
Q

What can nondisjunction cause in relation to reproduction?

A

A zygote would have an extra chromosome

20
Q

What is down syndrome?

A

A condition in which an individual has an extra or part of an extra chromosome 21.

21
Q

In down syndrome, where does the extra chromosome usually come from?

A

The mother

22
Q

The incidence rate of down syndrome increases as the mother ____

A

ages

23
Q

What 2 errors can happen during recombination?

A

Deletion or duplication of the genes that are to be crossed over

24
Q

What causes Di George syndrome?

A

A meiotic deletion in chromosome 22

25
Q

Give a brief summary on the discovery of the structure of DNA (4 events)

A
  • 1900s Kossel found the 4 bases
  • 1920s Levene determine that DNA is made of a string of nucleotides linked together in a chain
  • 1950 Chargaff found the proportions of the bases (A=T, C=G)
  • 1950s Watson+Crick examined X-ray image of DNA and proposed double helix model
26
Q

In the DNA double helix, the outside of the helix is made of the ______ ________ compounds and the rungs are made of the _________ _______. In addition, the strands go from 5’ to 3’ on one and __ to __ on the other

A

sugar-phosphate, nitrogenous bases, 3’, 5’

27
Q

How does DNA replication actually occur?

A

DNA unwinds by unzipping the base pairs. Then, new complementary strands are created on each split by DNA polymerase, resulting in 2 identical double helix stands

28
Q

What is gene expression? Describe the 4 steps

A

The conversion of DNA into a protein

  • DNA is transcribed into RNA by RNA polymerase
  • RNA is modified into mRNA and leaves the nucleus
  • mRNA is translated into an amino acid chain
  • The amino acid chain is folded into a protein
29
Q

What is an RNA triplet codon?

A

A series of 3 bases that translates into an amino acid.

30
Q

What is the purpose of the start and stop codon in mRNA?

A

It determines the start and end of a gene coding sequence

31
Q

How can each gene make more that one protein?

A

mRNA can be spliced in various ways to remove different regions (removing some exons and all introns)

32
Q

Where are proteins made?

A

On ribosomes located in the cytoplasm or attached to the rough endoplasmic reticulum

33
Q

How does mRNA and ribosomes make proteins?

A
  • mRNA attaches to ribosomes
  • Ribosome moves along the mRNA, reading the codons
  • As it moves, different tRNA molecules that have amino acids on one end and anti-codons on the other that match up with the base pairs attach to the mRNA
  • The polypeptide chains grows until the stop codon is reached
34
Q

The cell can regulate which genes are ________ by controlling the flow of information in gene expression

A

expressed

35
Q

What is gene regulation?

A

How a cell controls which genes are turned on and which genes are silenced

36
Q

Genes can be turned on or off based on _________________ signals

A

environmental

37
Q

How do transcription factors and promoters regulate gene expression?

A

DNA promoters are short regions of DNA upstream of the gene they regulate
Transcription factors are proteins that bind to the promoters. This binding initiates RNA transcription from the gene