G1- hitch hikers guide to human genome Flashcards Preview

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Flashcards in G1- hitch hikers guide to human genome Deck (47)
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1
Q

what is the replication of the human genome?

A

cell cycle and mitosis meisosis

2
Q

what is the organisation of genes?

A

Promotors, start codons, introns and exons

3
Q

What turns a gene into a protein?

A

Transcription, splicing and translation

post-translational modification and transport

4
Q

what provides variation in the human genome?

A

Polymorphisms

Mutations

5
Q

what contributes to disease?

A
  • genes

- environment

6
Q

what do genes control?

A

control predisposition to ALL common disease – eg. Caries, oral cancer

7
Q

what is genetics being increasingly used for?

A

determine treatment

8
Q

Describe the DNA structure.

A

• Strands of DNA pair up in an antiparallel fashion

• DNA is replicated and read
always in the 5’ –> 3’ direction
-bases are A,T, C, G

9
Q

How is information in DNA held?

A

held in the sequence of the bases which are held on a sugar/phosphate backbone

10
Q

what does the DNSA strand associate with?

A

associates with proteins (including histones) and is wound into a structure called a chomosome

11
Q

What are the stages of the cell cycle?

A
M-mitosis
G1- gap 1
Go-resting
S-synthesis (DNA)
G2-gap 2
12
Q

Describe DNA damage and repair.

A
  • DNA strand breaks
  • Chemical crosslinking
  • mismatched base
13
Q

when does DNA replication happen?

A

during S phase

14
Q

Describe key facts of DNA damage.

A
  • DNA can be damaged during replication
  • Repair mechanisms exist
  • Defects in these repair mechanisms cause disease
15
Q

What does mitosis produce from one diploid parent cell?

A

Two identical diploid daughter cells

16
Q

what does meiosis produce from one diploid parent cell?

A

4 Haploid daughter cells

one of each chromosome to each cell

17
Q

Describe crossing over at meiosis.

A

genes segregate independently, even if on the same chromosome

18
Q

what does meiosis occur?

A

Occurs in gamete formation

19
Q

what is different about RNA compared to DNA?

A
  • Single stranded
  • Ribose in backbone not deoxyribose
  • Uracil (U) is used instead of Thymine (T)
20
Q

what determines the amount of protein produced?

A
  • Rate of transcription (manufacture of Pre-mRNA)
  • Rate of splicing to mRNA
  • Half life of mRNA
  • Rate of processing of polypeptide
21
Q

Describe the change from DNA to protein.

A

-DNA is transcribed to pre mRNA
-Pre mRNA is spliced to mRNA
-mRNA is translated to protein
3 bases encode 1 amino acid or a stop
-Protein is modified and moved round the cell

22
Q

what causes sequence variations within a gene?

A
  • Changes in the promotor sequence
  • Changes in the exon sequence
  • Ones that change an amino acid
  • Sequence changes that do not
23
Q

what causes sequence changes in the DNA between genes?

A
  • Single Nucleotide polymorphisms (SNPs)

- Larger deletions or duplications

24
Q

what are polymorphisms?

A

-Any variation in the human genome that has a population frequency of greater than 1%

or

-Any variation in the human genome that does not cause a disease in its own right. It may however, predispose to a common disease

25
Q

what are mutations?

A

-A gene change that causes a genetic disorder. (a disease causing mutation)

Or

-Any heritable change in the human genome

26
Q

why do variants of genome all segregate independently of each other?

A

because of crossing over at meiosis

27
Q

what Is a genetic disease?

A

One caused by a change in the genes

28
Q

Name some of these changes in gene?

A
Extra piece of chromosome
Missing piece of chromosome
Change in gene sequence
Insertion or deletion of a few bases
Change of a single base where it matters
29
Q

what is the purpose of genome knowledge?

A

To know what a DNA test result means and use it for patient management

30
Q

what does phenotype equal?

A

genotype + environment

31
Q

what does all disease equal?

A

genes + environment

32
Q

what is penetrance?

A

The likelihood of having a disease if you have a gene mutation

33
Q

what does 100% penetrance mean?

A

you will always get the disease if you have the mutation

34
Q

what are mendelian disorders?

A

-Diseases that segregate in families in the manner predicted by Mendel’s Laws

-Essentially a disease that is predominantly caused by a change in a single gene
(High penetrance)

35
Q

what allows us to select one small pice of the human genome from a patient and amplify it?

A

Polymerase Chain Reaction (PCR) -make lots of copies of one short stretch of the genome

36
Q

what results from promotor mutation?

A
  • No, or reduced transcription

- No, or reduced protein

37
Q

what results from splice consensus altered?

A
  • mRNA decay

- Abnormal or absent protein

38
Q

what results from a base change makes a new stop?

A
  • mRNA decay]

- short or absent protein

39
Q

what results from base change that alters amino acid sequence?

A

different or non-functioning protein

40
Q

Name the types of mutation in DNA sequences.

A
  • wild type
  • stop
  • missense
  • insertion
  • deletion (out of frame)
  • deletion (in frame)
  • triplet expansion
41
Q

Can different mutations in the same gene cause the same disease?

A

Yes

42
Q

what effect does different mutations have?

A

have different effects on the protein produced and these can be predicted

43
Q

what is non-mendelian inheritance?

A

Everything else including common “multifactorial” diseases

44
Q

why sometimes is a child affected but neither parent seems to be affected?

A
  • New mutation occurs as genes transmitted to child
  • Parent doesn’t show clinical features but carries mutation (non-penetrance)
  • Parent carries mutation but has very mild disease (variable expressivity
45
Q

what different outcomes can gene mutations have?

A

-Mutations can affect the same gene in different ways,
Leading to different disease processes

but

-Mutations in different genes can also cause the same
Disease

46
Q

what is used to find out diagnosis?

A
  • clinical history
  • family history
  • clinical examinations
  • genetic tests
47
Q

what can we do with diagnosis?

A
  • recurrence risk
  • treatment
  • prognosis
  • genetic tests