Cellular control, OCR- Unit 5, module 1

Cellular control, OCR- Unit 5, module 1

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Sameer Biology
Jahabarali
Unit 5 Module 1 Cellular control
Protein synthesis
A gene is a length of DNA that codes for one or more
polypeptides, including enzymes. It occupies a specific region
(locus) within a chromosome (a long chain of supercoiled
nucleotide base pairs, associated with histone proteins), within the
nucleus, or some in the mitochondria, or chloroplast.
Genome is the whole length of the DNA of an organism.
The resources required for protein synthesis:
A genetic code- the sequence of nucleotide bases on a gene that provides the codes for the construction of
protein (large polypeptide with more than 100 amino acids) or polypeptides. The characteristic of the code
includes:
Codons (triplet code)- three nucleotide bases code for 1 amino acid
Degenerate code- most amino acid have more than one code
Initiation/ termination codes- codes that indicate start or stop
Widespread but not universal- genes code's for similar polypeptides in most organisms but not
always identical, due to mutation.
Messenger RNA- activated nucleotides
that is assembled as a copy of the
coding strand sequence in the in the
nucleus
Ribosomes- organelle that is synthesised in the nucleus from ribosomal
RNA and proteins made of two subunits. It enables mRNA to be translated
as mRNA fits between the groove the two subunits, as the ribosome
movies along to read the mRNA code.
Transfer RNA- length of RNA folded into a hairpin shapes with three
bases exposed where particular amino acids can bind. At the other end
are anticodons which temporarily bind to a complimentry codon.

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Sameer Biology
Jahabarali
Unit 5 Module 1 Cellular control
Transcription is the first stage of protein synthesis
whereby a genetic code is copied to mRNA (free
activated nucleotide, with two extra phosphate
group) roaming the nucleoplasm and is transported
to the ribosome, found in the cytoplasm.
A gene dips in to the nucleolus where the
hydrogen bonds between the
complimentary bases break (T-A, G-C).
RNA polymerase catalyses, activated RNA
nucleotides to bind to the complimentary
(hydrogen bonds form) bases (U-A, G-C).…read more

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Sameer Biology
Jahabarali
Unit 5 Module 1 Cellular control
Mutation is caused by mutagens which causes a change in the sequence of nucleotides in the DNA.…read more

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Sameer Biology
Jahabarali
Unit 5 Module 1 Cellular control
Polypeptides are not synthesised as the gene is not translated without the mRNA
When lactose availability is high:
Inducer molecule (Lactose) binds to the repressor
protein, causing the tertiary structure to be altered.…read more

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Sameer Biology
Jahabarali
Unit 5 Module 1 Cellular control
Apoptosis is programmed cell death that occurs in multicellular organism.…read more

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Sameer Biology
Jahabarali
Unit 5 Module 1 Cellular control
Meiosis
Sexual reproduction is achieved by meiosis to produce gametes (haploid cells, with half the chromosomes).
Gametes fuse together at fertilisation to produce a zygote (cell with new genetic code). Meiosis takes place
in two separate divisions, Meiosis I and Meiosis II.
During interphase the DNA replicates, to produce to identical sister chromatids and prepares for mitosis or
meiosis, by generating the necessary enzymes.…read more

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Sameer Biology
Jahabarali
Unit 5 Module 1 Cellular control
Meiosis II
Prophase II
Nuclear envelope breaks down again (most animals)
Nucleolus disappears, chromatin condenses and spindle forms
Metaphase II
Chromosomes line-up randomly in the equator of the spindle and attaches
to the spindle fibres at the centromere
Anaphase II
The centromeres divide and chromatids are pulled apart to opposite poles,
by the spindle fibres
Telophase II
Nuclear envelope forms over the four new haploid daughter nuclei
In animals four haploid cells through cytokinesis
In plants…read more

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Sameer Biology
Jahabarali
Unit 5 Module 1 Cellular control
Mutation- DNA mutation occurs during Interphase, when DNA replicates or Chromosome Mutation
occurs. (not specific to meiosis)
The genotype is the entire genetic makeup of an organism that is made up of two alleles of the same gene.
The alleles can either be:
Homozygous- Identical alleles
Heterozygous- different alleles
The phenotype is the observable characteristic expressed in the organism, either through the development
of the organism within the environment, or is determined by its genotype.…read more

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Sameer Biology
Jahabarali
Unit 5 Module 1 Cellular control
development of muscle weakness and early death by the 20s.
XD Y
XD XD XD XD Y
Xd XD Xd Xd Y
CR CR
CW CR CW CR CW
CW CR CW CR CW
CR CW
CR CR CR CW CR
CW
CW CR CW
CW
A roan cattle is a shorthorn cattle that has two
co-dominant alleles that codes for white and red
hairs.…read more

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Sameer Biology
Jahabarali
Unit 5 Module 1 Cellular control
Antagonistic interaction occurs when, the epistatic allele in the first locus, prevents the hypostatic allele in
the second locus from being expressed. It is not inherited and it decreases phenotypic variation. Epistasis of
homozygous alleles may be:
Recessive (e.g.…read more

Comments

sara

Your work is amazing, its really helpful. Have you done responding to the environment biology module 4?

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