Brainscape's Knowledge GenomeTM

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


See full index

BIO > Cellular Control > Flashcards

Cellular Control Flashcards

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

What is a mutation?

A

A spontaneous change in the sequence of nucleotides in a DNA molecule of an organism.

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

What is a germ-line mutation and what is their significance?

A

A mutation in a gamete (germ cell).

These mutations provide the variation necessary for evolutionary change, as they can be passed on to offspring.

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

What is a mutagen?

A

An agent that increases the rate of mutation.

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

How do chemical mutagens cause mutation?

A

React with the bases, causing them to pair wrongly.

Or, become incorporated into the DNA.

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

How do physical mutagens cause mutation?

A

Damages DNA by altering the sugar-phosphate backbone.

E.g: ionising radiation.

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

How do biological mutagens cause mutation?

A

Viruses inject DNA into the host cell’s genome.

Bacteria produce toxins that can be chemical mutagens.

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

What is a point mutation?

A

Changes to a single base

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

Which kinds of mutation result in a frameshift mutation?

A

Insertion or deletion

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

What is a frameshift mutation?

A

Results in all amino acids for that gene being incorrect due to the triplet nature of DNA, unless the insertion or deletion is a multiple of 3.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a substitution mutation?

A

Where one or more bases are replaced by others.

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

What are chromosome mutations?

A

Changes to the structure or amount of a chromosome.

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

What is monosomy?

A

One chromosome instead of a pair.

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

What is trisomy?

A

3 chromosomes instead of 2.

e.g: down syndrome

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

What are the 3 types of mutation?

A

Beneficial.
Harmful.
Neutral.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is an example of a beneficial mutation?

A

Antibiotic resistant bacteria.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are 3 examples of harmful mutations?

A

Sickle-cell anaemia
Cystic fibrosis
Down syndrome

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

How do beneficial and harmful mutations result in changes to the organism?

A

By changes to proteins resulting from their primary structure being altered.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why are the majority of mutations neutral?

A

Due to the degenerate nature of the genetic code, the mutation could result in the same amino acid being produced.
Even if a different amino acid is produced, it may not affect the secondary/tertiary structure of the protein, so the protein would function as normal.

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

What mutation causes sickle-cell anaemia?

A

A substitution point mutation in the beta-polypeptide chain of a haemoglobin molecule.
Results in a valine coded for instead of glutamate.

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

What is the effect of the sickle-cell anaemia mutation?

A

Results in a “sickle-shaped” erythrocyte.

  • cannot carry oxygen as well.
  • gets stuck in capillaries.
  • shorter cell life span.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the lac operon an example of?

A

Enzyme induction.

Transcriptional level control of gene expression.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is enzyme induction in bacteria?

A

Bacteria vary the rate of enzyme synthesis in response to environmental changes.

23
Q

What does the bacterium E. coli need the lac operon for?

A

E. coli usually uses glucose as a respiratory substrate, but it can use lactose if there is an absence of glucose.
E. coli requires the enzyme beta-galactosidase to metabolise the hydrolysis reaction of lactose to glucose and galactose.

24
Q

What is the function of the promoter regions on the lac operon?

A

The promoter is where RNA polymerase binds.

25
Q

What is the function of the regulatory gene on the lac operon?

A

Codes for the repressor protein.

26
Q

What is the role of the operator region on the lac operon?

A

Where the repressor protein binds.

27
Q

What are the enzymes that the structural genes of the lac operon code for?

A

Beta-galactosidase
Beta-galactoside permease
Beta-galactoside acetyltransferase (not yet fully understood)

28
Q

What is the role of Beta-galactosidase?

A

Cleaves lactose into glucose and galactose.

29
Q

What is the role of Beta-galactoside permease?

A

Membrane transport protein (channel protein) allowing lactose into the cell via facilitated diffusion.

30
Q

What happens on the lac operon if lactose is not present?

A

RNA polymerase binds to the regulatory gene.
The regulatory gene is transcribed.
The repressor protein is translated at the ribosome.
The repressor protein binds to the operator region. blocking RNA polymerase.
This prevents the lac structural genes from being transcribed.

31
Q

What is the structure of the repressor protein?

A

Has two binding sites, one for lactose and one for the operator region of the lac operon.
If lactose is in high enough concentration, it will bing to the repressor protein, changing the 3D shape of its other active site so it can no longer bind to the operator. (allosteric inhibition)

32
Q

What happens at the lac operon if lactose is present?

A

Lactose binds to the repressor protein, causing allosteric inhibition.
This prevents the repressor protein binding to the operator, allowing RNA polymerase to transcribe the lac structural genes.
The enzymes are translated.
Lactose is allowed into the cell via facilitated diffusion.
Lactose is hydrolysed.

33
Q

What is the role of cyclic AMP in the functioning of the lac operon?

A

The rate of transcription at the lac operon is only fast enough to produce the number of enzymes required to metabolise lactose if the secondary messenger cAMP is bound to RNA polymerase.
The presence of glucose decreases cAMP levels.
=>if glucose and lactose are both present, glucose will be metabolised, not lactose.

34
Q

What are the levels of control of gene expression? (3)

A

Transcriptional (turning genes on/off)
Post-transcriptional (modification of mRNA)
Post-translational (proteins modified after synthesis)

35
Q

What are examples of transcriptional level gene expression control?

A

Lac operon => cyclic AMP
Chromatin remodelling
Histone modification

36
Q

What is chromatin remodelling?

A

During cell division, chromatin is tightly wound around histone proteins (heterochromatin), so no proteins can be transcribed.
During interphase, the chromatin is loosely wound (euchromatin), so proteins can be transcribed and synthesised.

37
Q

What is histone modification?

A

Individual histones can be modified, making a section of DNA (gene) looser/tighter, allowing/preventing transcription.

38
Q

What are the two main processes at the post-transcriptional level of gene expression control?

A

RNA processing

RNA editing

39
Q

What happens in RNA processing?

A

A cap is added to the 5’ end and a tail to the 3’ end. (stabilises the mRNA delaying degradation in the cytoplasm and aids binding of mRNA to ribosomes)
Splicing occurs:
-introns (non-coding regions) are removed.
-exons (coding regions) are joined together.

40
Q

What happens in RNA editing?

A

The nucleotide sequence of mRNA is modified through base addition, deletion or substitution.

41
Q

What happens at the post-translational level of gene expression control?

A

The addition of non-protein groups.
Modification of amino acids and the formation of bonds (folding).
Proteins can be activated by cAMP.

42
Q

What is morphogenesis?

A

The shaping of an organisms and its parts.

43
Q

What does pattern formation refer to in developmental biology?

A

In eukaryotic organisms, signals contribute to morphogenesis and cell differentiation.

44
Q

What is the difference between how plants/fungi and animals carry out morphogenesis and cell differentiation?

A

In animals this mainly happens during the embryonic stage.

In plants and fungi this happens continually, their morphology is more determined by environmental factors.

45
Q

What are homeobox genes?

A

DNA sequences containing a homeobox sequence (codes for a homeodomain), which are involved in the regulation of patterns of development (morphogenesis) and cell differentiation in eukaryotic organisms.

46
Q

What does it mean that homeobox genes are highly conserved?

Why is this the case?

A

Homeobox genes are very similar throughout eukaryotic organisms.
This is due to their importance to the survival of an organism.

47
Q

What is the function of a homeodomain?

A

Homeodomains are transcription factors.
The homeodomain binds to DNA and initiates transcription.
This allows one homeobox gene to “switch on” many other genes.

48
Q

What is the name given to the homeobox genes that animals have?

A

Hox genes.

49
Q

What do we know about the evolutionary development of hox genes?

A

Increases in the number of hox genes led to a greater complexity of body structure.
Hox gene clusters probably arose through gene duplication of homeobox clusters.

50
Q

Why were homeobox genes first studied in fruit flies?

A

They:

  • are small
  • are easy to keep
  • have a short life cycle
  • have only 4 chromosomes
  • readily exhibit mutation (after inbreeding/X-ray treatment)
51
Q

What is the difference between extrinsic and intrinsic inducers of apoptosis and mitosis?

A

Extrinsic inducers are extracellular signals.

Intrinsic inducers are intracellular signals usually a result of cellular stress.

52
Q

What are some examples of extrinsic inducers? (3)

A

Hormones (e.g: growth factors stimulate mitosis)
Toxins
Cytokines

53
Q

What are some examples of intrinsic inducers? (4)

A

Anoxia or nutrient stress (anoxia is severe hypoxia).
Viral infection
Heat stress
Radiation

54
Q

Outline the 6 stages of apoptosis.

A
  1. Cell shrinkage and rounding due to the breakdown of the cytoskeleton by enzymes. The cytoplasm appears less dense.
  2. Cell membrane shows irregular buds known as blebs.
  3. Chromatin undergoes condensation into compact patches.
  4. The nuclear membrane becomes discontinuous as DNA is degraded.
  5. The cell breaks apart into several vesicles called apoptotic bodies.
  6. The apoptotic bodies are phagocytosed.

BIO (33 decks)

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