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biology > 8.1 + 8.2 > Flashcards

8.1 + 8.2 Flashcards

1
Q

what re 6 types of mutation

A
  1. substitution - one or more bases swapped for another
  2. inversion - a sequence of bases are reversed
  3. insertion - one or more bases added
  4. deletion - one or more bases are removed
  5. duplication - one or more bases are repeated
  6. translocation - a sequence of bases is moved from one location in the genome to another
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2
Q

why can frame shifts be detrimental

A

as if changing the number of bases in the DNA code then this can shift all the base triplets that follow so that all the codons after the mutation are changed and the DNA will be transcribed differently

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3
Q

what are the 4 types of stem cells

A

totipotent stem cells
pluripotent stem cells
multi potent stem cells
unipotent stem cells

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4
Q

describe totipotent stem cells

A

cells that can differentiate into embryonic tissues, they form from the the embryo and placenta
all genes in nucleus are able to be activated

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5
Q

describe pluripotent stem cells

A

also found in embryos and vast majority of genes are still able to be activated

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6
Q

describe multipoint stem cells

A

found in mature mammals, some genes have been switched off but they have the genes for some different cells still available

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7
Q

describe unipotent stem cells

A

cells that can only form one other type of cell, example is cardiomyocytes that can divide to form other heart muscle cells

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8
Q

what are adult stem cells

A

obtained from the body tissues found in the bone marrow these are multipotent

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9
Q

what are induced pluripotent stem cells

A

produced in a lab specialised from adult stem cells to become pluripotent. there cells express a series of transcription factors which are normally expressed by pluripotent stem cells.
good as if from patients own cells there will be no rejection

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10
Q

how is a gene expressed

A

when is is trancribed into mRNA and then translated into a protein

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11
Q

what are transcription facotrs

A

proteins which travel into the nucleus and control the rate of transcription by activating or repressing RNA polymerase

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12
Q

how to transcription factors work

A

bind to the promotor region which is the binding site of RNA polymerase and therefore the starting point for transcription of that gene

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13
Q

how can transcription factors be turned off

A

by inhibitor molecules. if these bind to the transcription factors it can prevent it from attaching to the promoter region.

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14
Q

how does oestrogen act as a transcription factor

A

oestrogen binds to a transcription factor called oestrogen receptor forming an oestrogen-oestrogen receptor complex
this complex moves into the nucleus binding to the hormone receptor in the promote region of that gene either activating or repressing transcription

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15
Q

what is iRNA

A

interfering RNA which are small lengths of non-coding RNA.

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16
Q

what do iRNA do

A

regulate gene expression by affecting translation, these are double stranded and stop mRNA that have been transcripts already from being translated into a protein

17
Q

what are the two types of iRNA

A

siRNA (short interfering) - only in animals
miRNA (micro RNA) - in plants and animals

18
Q

how do siRNA and miRNA (in plants) work

A
  • double stranded siRNA associates with proteins in the cytoplasm and unwinds
  • one of the siRNA strands is chosen and the other breaks down
  • Single strand of siRNA binds to the target mRNA
  • the proteins associated with the siRNA cut the mRNA into small fragments so it can no longer be translated
  • the mRNA fragments then move into a processing body breaking them down
19
Q

how do miRNA work in mammals

A
  • miRNA precursor folds back in itself held together by hydrogen bonds
  • an enzyme called diet moves along the double stranded RNA cutting it into segments
  • one strand of each short double-stranded RNA is broken down and the other associates with proteins
  • the bound miRNA can base-pair with any target mRNA that is complementary
  • the miRNA protein complex prevents gene expression by either breaking down the target mRNA or by blocking its translation
20
Q

what are the 2 types of genes that control cell division

A
  • proto-oncogenes which cause cancer when turned on
  • tumour suppressor genes which cause cancer when turned off
21
Q

how to proto-oncogenes work

A

normally help cells grow however if they mutate the can become permanently activated. when this happens cell divide out of control leading to cancer.if it mutates this is called oncogene

22
Q

how do tumour suppressor genes work

A

normally help slow down cell division, repair DNA mistakes or tell cell when to die however when they dont work cells can grow out of control

23
Q

4 differences between benign and malignant tumour

A

bengin non-cancaours, slow growing, doesn’t metastasise and do have normal shape where malignant are cancerous, fast growing, invade and destroy other tissues through metastasis and may have an abnormal shape

24
Q

how can oestrogen cause cancer and how increase oestrogen levels

A

increased oestrogen for an extended period of time is thought to increase chances of breast cancer as it stimulates more breast tissue to divide hence increasing chance of mutation

  • taking birth control
  • starting menstruation early
  • starting menopause late
25
Q

5 examples of cancer treatment

A
  • surgery to remove specific tumour if it hasn’t already spread
  • immunotherapy can help direct treatments to cancerous cell reduce side affects
  • chemo which prevents the synthesis of enzymes required for DNA replication
  • radiotherapy damages DNA which therefore not pass through the S phases forcing apoptosis
  • drugs preventing spine fibres forming
26
Q

3 differences of genome and epigenome

A
  • epigenome is the tags on the histone proteins which are associated with DNA where the genome is the sequence of bases in the entire DNA molecule of an orgaism
  • epigenome tags can respond to external factors and change gene expression where genome can only be affected by mutations
  • environmental factors can influence the epigenome where environmental factors can only influence the genome if cause a mutation
27
Q

what does increasing the methylation of DNA do

A

this alters the DNA structure preventing transcription factors and enzymes from binding to it. DNA methyltransferase enzymes attach the methyl group to cytosine baes on the DNA molecule

28
Q

what does acetylation of histones do

A

when histones are acetylated the DNA loosens from the histones making it less condensed. this means the transcription factors and enzymes can bind to the DNA and transcribe it. When acetyl groups are removed from the hirsute the chromatin condenses and transcription fac

29
Q

what is hypermethylation and what does it do

A

hypermethylation of tumour suppressor genes prevents them from being transcribed, the proteins they normally produce which slow down cell division will not be made. this can cause cells to divide uncontrollably by mitosis and form tumours
hypomethylation of proto-oncogenes causes them to act as oncogenes and produce proteins that encourage cell division.

30
Q

how can epigenetics treat diseases

A
  • drugs that stop DNA methylation can prevent genes from being switched off so they can be transcribed and produce proteins what when missing cause symptoms of the disease
  • HSAC inhibitor drugs such as romidepsin can be used to prevent decreased acetylation of histones which can stop some genes from being turned off, they work by inhibiting the activity of deacetylase enzymes so that the gene remain uncondensed and can be transcribed
31
Q

why can inheriting epigenetic changes be an advantage

A

as it allows the inheritance of behaviours which will make offspring automatically adapted/prepared to deal with environmental changes when they are born

biology (30 decks)

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