Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > Genetics- Cellular Control > Flashcards

Genetics- Cellular Control Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is a gene?

A

A short section of DNA that codes for a polypeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a mutation?

A

An error in a gene caused by a change in base sequence of DNA of an organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the features of mutations?

A

Are sudden, significant and random

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What do mutations cause?

A

An unpredictable form of variation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why might a mutation NOT be significant?

A
  • Genes are only a small part of DNA

- DNA is degenerate, so a polypeptide can be coded for more than one gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why do mutations cause changes in phenotype?

A

Mutation creates a change in primary sequence (base of amino acids). This causes different bonds to break and be made, changing the specific tertiary shape of proteins. This can cause genes to stop working.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a somatic mutation?

A

A mutation in non-reproductive cells that cannot be inherited

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a germ-line mutation?

A

A mutation in an organism’s gamete which can be inherited by offspring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the process of antibiotic resistance?

A
  • There is a spontaneous mutation in a growing population in a bacterial population
  • The population is exposed to antibiotics
  • The resistant bacteria survives and reproduces to generate a population of antibiotic resistant bacteria
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the causes of mutations?

A

-Natural and spontaneous during meiosis (multicellular) and mitosis (unicellular)
-Transcription mistake
-Produced by mutagens, such as:
Viruses, Chemicals and Radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How can chemicals cause mutations?

A

Some chemicals are deaminating agents, which can turn cytosine into uracil, changing the base sequence. Also have alkylating agents that add methyl or ethyl groups, resulting in incorrect base pairing during replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do viruses cause mutations?

A

Viruses insert their own genetic material (RNA,DNA) into the host cell, overriding DNA replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does radiation cause mutations?

A

Effects depend on the wavelength and dose of radiation received. Ionising radiation like X-Ray can break one or both DNA strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the different types of transcriptional errors?

A
  • Insertion (Addition) or Deletion of a nucleotide
  • Substitution of a nucleotide
  • Inversion of two nucleotides
  • Insertion creates a frameshift
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Transcriptional error example

A 
AGT CCC AAA CCA original
AGT ACC CAA ACC A insertion
AGC CCA AAC CA deletion
AGT TCC AAA CCA substitution
AGC TCC AAA CCA inversion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What causes sickle cell anaemia?

A

A base substitution, where A has been replaced by T. So CAT is replaced by CTT. This means that during translation, the mRNA causes valine to be added to the polypeptide instead of glutamate. There haemoglobin S is formed which is much less soluble and hence forms sticky fibres which distort the erythrocyte

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the types of chromosome mutation?

A
  • Deletion, where bits of chromosome break off and are lost
  • Duplication (section of chromosome gets copied)
  • Translocation, where a section of DNA breaks off and joins another non-homologous chromosome
  • Inversion, where a section of chromosome breaks off, is reversed and then joins back onto the chromosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is Downes Syndrome?

A

A genetic disorder caused by an extra chromosome 21.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What causes Downes Syndrome?

A

Caused by non-disjunction, which means there is an uneven distribution of parental chromosomes at meiosis. This leads to a trisomic cell with 3 chromosomes 21, instead of 2.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the characteristics of Downes Syndrome?

A
  • Broad forehead
  • Short neck
  • Fold in eyelid
  • Spots in iris
  • Short nose
  • Protruding tongue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How can genes be regulated?

A
  • Transcriptionally
  • Post transcriptionally
  • Translationally
  • Post translationally
22
Q

How can genes be regulated transcriptionally?

A

Genes turned on or off e.g Lac Operon

23
Q

How can genes be regulated post-transcriptionally?

A

mRNA stopped from reaching ribosomes so no translation

24
Q

How can genes by regulated translationally?

A

Translation stopped and started at ribosomes

25
Q

How can genes be regulated post-translationally?

A

Proteins can be modified after translation to change the 3D shape

26
Q

What mechanisms affect transcriptional control?

A
  • Chromatin remodeling

- Histone modification

27
Q

What is chromatin remodeling?

A

Heterochromatin is tightly wound DNA visible during cell division, whereas euchromatin is loosely wound DNA during interphase. Transcription of DNA not possible when DNA is tightly wound because DNA polymerase cannot access the genes. Whereas the genes in euchromatin can be easily transcribed. Protein synthesis only occurs during interphase therefore the presence of euchromatin only during this time is a form of regulation.

28
Q

What is histone modification?

A

DNA coils around histones. Histones can be modified to increase or decrease the degree of packing. Acetylation and phosphorylation reduces the positive charge on histones, causing DNA to coil less tightly, allowing certain genes to be transcribed. Methylation of makes the histones makes the histones more hydrophobic so they bind more tightly to each other, causing DNA to coil tighter. This prevents the transcription of certain genes.

29
Q

What is an operon?

A

A group of genes that are transcribed at the same time

30
Q

What do operons control?

A

Important biochemical processes

31
Q

What is the Lac Operon?

A

A collection of three genes that specify proteins that help the bacterial cells utilize lactose.

32
Q

What do the genes in the Lac Operon control?

A

LacZ: encodes for an enzyme that splits lactose into monosaccharides
LacY: encodes a membrane-embedded transporter that helps bring lactose into the cell

33
Q

What does the Lac Operon contain?

A
  • CAP site
  • Promoter
  • Operator
  • Three genes
34
Q

What happens when there is no lactose?

A

The lac repressor is bound to the operator so no transcription occurs as this save resources as the enzymes for hydrolysis are not needed

35
Q

What happens where there is lactose and glucose?

A
  • Allolactose binds to lac repressor
  • Lac repressor cannot bind to operator
  • Transcription occurs
  • Low cAMP means CAP cannot bind to CAP site
  • However CAP isn’t needed due to lower demand for transcription as there is a ready supply of glucose
36
Q

What happens when there is lactose and no glucose?

A
  • Allolactose binds to lac repressor
  • Lac repressor cannot bind to operator
  • Transcription occurs
  • CAP binds to CAP site as cAMP is present
  • Promotes further transcription as there is an urgent need for glucose (increase rate of hydrolysis)
37
Q

What is morphogenesis?

A

Shaping of an organisms by embryological processes of differentiation of cells, tissues and organs and the development of organ systems

38
Q

Why are fruit flies often studied in genetics?

A
  • Fast reproduction rate
  • Little ethical issues
  • Small, easily contained
39
Q

What is a homeobox?

A

DNA sequence around 180 base pairs long found within genes that are involved in the regulation of patterns of anatomical development

40
Q

What are Hox Genes?

A

Group of related genes that control the body plan of an embryo along the head-tail axis. They determine the type of segment structures will form on a given segment

41
Q

Why do common patterns of genetic control exist?

A

Because all the genes have descended from the genes of common ancestors

42
Q

How do Hox Genes work?

A

The protein product of each Hox Gene is a Hox protein which is a transcriptional factor. They are capable of binding to specific nucleotides sequences on the DNA called enhancers where they either activate or repress genes.

43
Q

What is epigenetics?

A

Control of gene expression by the modification of DNA

44
Q

What is post-transcriptional control?

A

Pre-mRNA needs to be converted to mature mRNA before translation can occur. A cap (modified nucleotide) is added to 5’ end and a tail (long chain of adenine) is added to 3’ end. Splicing also occurs.

45
Q

What is RNA splicing?

A

In order to become mature mRNA, RNA is spliced at specific points. The introns (non-coding DNA) are removed and the exons (coding DNA) are joined together.

46
Q

What is post-translational control?

A

Proteins can be modified after synthesis which changes their functions

47
Q

Why is apoptosis important in shaping organisms?

A

It removes unwanted cells and tissues in order to sculpt certain features. For example, the removal of skin between our fingers so they are no longer webbed. Also, cells undergoing apoptosis can release chemical signals which stimulate mitosis and cell proliferation, leading to the remodelling of tissues

48
Q

Why is mitosis important in shaping organisms?

A

Increases the number of cells, leading to growth of limbs and other features

49
Q

How is mitosis and apoptosis regulated?

A

Hox genes

50
Q

What factors can affect the expression of regulatory genes?

A

Can be influenced by internal and external factors. Stress, when the homesostatic balance is upset, can have an impact on the growth and development of an organism. As well as, internal factors like hormones. Drugs can also affect the activity of regulatory genes

Biology (33 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions