Molecular Biology Wk 2

Question 1

Describe the structure of prokaryotic cells

Answer 1

Typically, spherical rod like or corkscrew shaped
They often have a protective coat or cell wall surrounding the plasma membrane which encloses single compartment containing the cytoplasm and the dna

However, under optimal conditions many prokaryotic cells can duplicate in as little as 20 mins

In 11 hours by repeated divisions a single prokaryote can give rise to more than 8 billion progeny ( exceeds the total number of humans on earth)

Question 2

What are the two main domains of prokaryotic cells

Answer 2

Bacteria

Archaea - members of archaea are more closely related to eukaryotes than they are to the other groups of prokaryotes ( bacteria)

Question 3

What are archaea

Answer 3

They are best known to live in extremely inhospitable environments and they are often referred to as extremophiles

Included among the archaea are…
Methanogens- capable of producing co2 and h2 gases into methane gas

Halophiles - prokaryotes that live in extremely salty environments such as the Dead Sea or certain deep seas brine pools

Acidophiles- acid loving prokaryotes that thrive at a ph of as low as 0 such as those found in in drainage fluids or abandoned mine shafts

Thermophiles- prokaryotes that live at very high temperatures

Hyperthermophiles - live in hydrothermal vents of the ocean floor

Question 4

What are domain bacteria

Answer 4

Includes the smallest known cells called mycoplasma which lack a cell wall and contain a genome with fewer than 500 genes

Question 5

What is Cyanobacteria

Answer 5

Most complex of all prokaryotes
Contain elaborate arrays of cytoplasmic membranes, which serve as a site for photosynthesis

As in plants, photosynthesis of Cyanobacteria is accomplished by the splitting of water molecules which releases molecular oxygen

Question 6

Where is an unusual place for Cyanobacteria bacteria to live

Answer 6

In the hairs of polar bears

Question 7

What are Cyanobacteria also capable of

Answer 7

Nitrogen fixation - conversion of nitrogen gas into reduced forms of nitrogen ( such as ammonia NH3)

Question 8

LOOK AT GOODNOTES MOL BIO IMAGES

Question 9

Types of eurkayotic cells

Answer 9

The most complex eukaryotic cells are not found in plants and animals but in unicellular protists

All of these complex activities such as sensing the environment, trapping food, expelling excess fluid and evading predators is all confined in this one cell- (amoebas, euglena, plasmodium)

Question 10

What are the characteristics of protists

Answer 10

They are eukaryotic which means they have a nucleus
Most have mitochondria
They can be parasites
Prefer moist and aquatic environments

Question 11

Describe the process of cell differentiation

Answer 11

An alternative pathway has led to the evolution of multicellular organisms in which different activities are conducted by different types of cells -

Specialised cells are formed for a process called differentiation

Question 12

Describe the process of differentiation in a fertilised human egg

Answer 12

Embryonic development will lead to the formation of approx 250 distinct types of differentiated cells

The pathway of differentiation depends primarily on the signals received from the surrounding environment - this determines the position of the embryo

Question 13

Name the six model organisms

Answer 13

A bacterium (prokaryote)

(Eukaryote)
Budding yeast
Flowering plants
A nematode
A fruit fly
A mouse

Question 14

LOOK AT GOODNOTES MOL BIO IMAGES

Question 15

Explain the studying of a human disease for example Colton cancer using E. coli

Answer 15

Basic steps of DNA repair are the same in both organisms and a gene involved in dna repair (mutL IN E. coli and MLH1 in humans is found in both organisms

E. coli has an advantage of being easier to grow and researchers can easily study new mutations in the bacterial mutL gene in order to figure out how it works

Found on chromosome 3

Question 16

Health conditions related to genetic changes in MLH1 gene

Answer 16

Lynch syndrome - hereditary nonpolypopis colorectal cancer

Ovarian cancer

Question 17

What diseases is the fruit fly being used for

Answer 17

Mutant genes in the fruit fly produce phenotypes with structural abnormalities of the NS and adult on set degeneration of the NS

Huntingdon disease
Machado- Joseph disease
Myotonic dystrophy
Alzheimer disease

Question 18

What is Huntington disease

Answer 18

Is a progressive brain disorder that causes uncontrolled movements, emotional problems and loss of thinking ability

Mutations on the HTT gene cause this disease

HTT provides instructions for making a protein called huntingtin
Located on chromosome 4

Question 19

What is Machado Joseph disease

Answer 19

• is a condition characterised by progressive problems with movement. People usually experience problems with coordination and balance (ataxia). Other early signs and symptoms include speech difficulties, uncontrolled muscle tensing (dystonia), muscle stiffness (spasticity), rigidity, tremors, bulging eyes, and double vision.

This results from a mutation in the ATXN3 gene know as trinucleotide repeat expansion. The mutation increases the length of the repeated CAG segment in the gene.

Located on chromosome 14

Question 20

What is myotonic dystrophy

Answer 20

Part of a group of inherited disorders called muscular dystrophies

Characterised by progressive muscle wasting and weakness.

Question 21

What are the two types of myotonic dystrophy

Answer 21

Type 1 and 2

Muscle weakness associated with type 1 particularly affects lower legs, hands and neck and face

Muscle weakness in type 2 primarily involves the muscles of the neck, shoulders, elbows and hips

Different types are caused by mutations in different genes

Question 22

Mutations of myotonic dystrophy

Answer 22

Type 1 is caused by mutations in the DMPK gene while type 2 results from mutations in the CNBP gene.

CNBP- located on chromosome 3

DMPK- located on chromosome 19

Question 23

What is Alzheimer’s disease (ad)

Answer 23

Approx. 10 percent of familial ad exhibits autosomal dominant inheritance ; the remainder exhibits multifactoral inheritance.

Defects of the beta amyloid precursor protein metabolism cause neuronal dysfunction and death observed with AD.

Presenelin 1,2 gene, when any gene is altered large a sounds of toxic protein fragment called amyloid beta peptide are produced in the brain- leads to death of nerve cells

People with Down syndrome have an increased risk of getting AD

Question 24

What disease is nematode being used to study

Answer 24

Diabetes
Insulin dependent diabetes mellitus (IDDM)
Insulin resistant diabetes

Question 25

What causes IDDM type 1

Answer 25

• autoimmune destruction of islet beta cells in the pancreas
• auto reactive Tcells lead to the destruction of the islet cells in the pancreas
• the destruction of islet beta cells causes an insulin deficiency and thereby the dysregulation of anabolism and catabolism resulting in metabolic changes

Question 26

What are the two units of linear measure

Answer 26

• micrometers
• nanometers

Question 27

Size of the nucleus in diameter

Answer 27

5-10 micrometer

Question 28

Size of mitochondria

Answer 28

• is 2 micrometers in length

Question 29

Size of prokaryotic cells

Answer 29

1 to 5 micrometer in length

Question 30

Size to eukaryotic cells

Answer 30

About 10 to 30 micrometer

Question 31

What features are viruses characterised by

Answer 31

Particles composed of an internal core containing either dna or rna (but not both) covered by a protective protein coat

Obligate intracellular parasites
Viruses replicate in a manner different from that of cells

One virus can replicate to produce hundreds of progeny viruses

Question 32

How are the shapes of virus particles determined

Answer 32

Arrangement of repeating subunits formed by the protein coat of the virus

Most viruses appear as spheres or rods in the EM

20 to 300 nm in diameter

Question 33

What is insulin resistant diabetes type 2

Answer 33

Antibodies to insulin receptors have demonstrated that interfere with insulin binding

Question 34

Symptoms of diabetes

Answer 34

Blurred vision
Weight loss
Lethargy
Nausea
Vomiting