Cellular control

What do genes code for?

The genetic code is a duplet, degenerate code

A gene to be [blank_start]transcribed[blank_end] unwinds and unzips. The length of DNA that makes up the gene dips into the [blank_start]nucleolus[blank_end]. [blank_start]Hydrogen[blank_end] bonds between [blank_start]complementary[blank_end] bases break. RNA nucleotides bind to their exposed complementary bases. This is catalysed by [blank_start]RNA polymerase[blank_end]. The two extra [blank_start]phosphates[blank_end] are released which releases energy for bonding adjacent nucleotides. The mRNA is complementary to the nucleotide base sequence on the [blank_start]template[blank_end] strand of the DNA. Therefore it is a [blank_start]copy[blank_end] of the base sequence on the [blank_start]coding[blank_end] strand of the length of DNA. The mRNA is released from the DNA and passes through a [blank_start]nuclear pore[blank_end] to a [blank_start]ribosome[blank_end].

How does cyclic AMP activate proteins?

Mutations cause changes to the sequence of amino acids in DNA molecules

When lactose is [blank_start]absent[blank_end] from the growth medium: The regulator gene is expressed and the [blank_start]repressor[blank_end] protein is synthesised. It has two binding sites, on the binds to [blank_start]lactose[blank_end] and one that binds to the operator [blank_start]region[blank_end]. The repressor [blank_start]protein[blank_end] binds to the operator region. In doing so it covers part of the [blank_start]promoter[blank_end] region, where RNA [blank_start]polymerase[blank_end] normally attaches. RNA polymerase cannot bind to the promoter region so the [blank_start]structural[blank_end] genes cannot be transcribed into [blank_start]mRNA[blank_end]. Without mRNA these genes cannot be [blank_start]translated[blank_end] and the enzymes cannot be synthesised.

Genes that control development of body plans are similar in plants, animals and fungi

Which of these statements are true about apoptosis?

How many stages are there in meiosis?

An allele is a version of a [blank_start]gene[blank_end]. A gene is a length of DNA that codes for one or more [blank_start]polypeptides[blank_end]. The locus is the [blank_start]position[blank_end] of a gene on a chromosome. [blank_start]Crossing[blank_end] over is when lengths of DNA are swapped from one chromatid to another.

The genotype refers to the characteristics that are expressed in the organism. The phenotype is the genetic makeup of an organism.