Biology Year 13 Random Retrieval

What causes epigenetic markers to be added or removed from DNA?

The mRNA travels to the ribosome, where it feeds between the two subunits, exposing the template bases. tRNA molecules each carry a specific amino acid at the top, with a complementary sequence of three bases called an anti-codon at the bottom. The tRNA anticodons then complementary base pair with the mRNA ____8____.

In the ribosome there are 3 binding sites for tRNA, two where a ____9____ bond is formed between the carried amino acids. These amino acids then form a ____10_____ chain which leaves the ribosome. The third site is a departure site, where the tRNA which has released its amino acid departs to pick up a new amino acid.

Once the entire mRNA sequence has been ____11____, it can either pass into another ribosome to make another polypeptide or be degraded.

Which of the following would NOT increase your exposure to oestrogen?

Fill in the missing word : Causes of Mutations A mutation is any change to the order of __12___ in the genetic code. These occur naturally as the enzyme _____13_____ replicates the DNA and makes mistakes. The incidence can also be produced due to exposure to certain agents called mutagenic agents.

These can be chemicals such as nitrous acid, which converts cytosine to uracil. Nitrous acid would therefore cause a __14___ mutation. Ethidium Bromide is used to stain DNA during gel electrophoresis. It can insert between bases, acting in a similar way to an addition mutation and therefore causing a __15___ along the rest of the gene. UV radiation is also a mutagenic agent.

It can cause bonds to form between pyrimidine bases ( thymine and cytosine). This bonding causes polymerases to misread or stop working all together at that point.

What is it called when succession is stopped artificially?

Tay Sachs is a recessive disease which leads to the build up of certain lipids which eventually become toxic. The Cajun community in the USA has an incidence of about 1 in every 3,500 births. What is the number of homozygous dominant healthy individuals in a Cajun population of 100,000 people?

A group of organisms of the same species living in a particular area at a particular time' is the definition for what?

What is the definition of a species?

Marfan syndrome is a dominant inherited disorder, where the suffer develops an increase in a growth factor ( TGF - beta) which effects connective tissue. What is the probability of a healthy mother and a heterozygous father having a healthy child?

What is the definition of 'allele'?

Doctors investigated two ways of measuring the effect of general anaesthetics. In one method they timed how long it took to stop blinking, and then repeated the investigation using a machine to record when brain activity showed they were unconscious. Blinking involves cholinergic synapses. Anaesthetic S is a similar shape to acetylcholine. Suggest how anaesthetic S stops the transmission across the synapse.

What is the main function of the fatty substance wrapped around peripheral nerve axons?

True or False: If too few sodium channels are opened by a stimulus on an neurone membrane, then no action potential is generated.

Name protein B in the above diagram.

What does Darwin's experiment where he removed a shoot tip then replaced it show?

Which would be the most accurate method of sampling dry biomass?

Which two processes turn Citrate into the 5C intermediate?

How many carbons are present in glucose phosphate?

How many molecules of ATP are required to generate TWO molecules of glucose ?

Which substance goes on to create other organic molecules?