R M Cullen MD MSc MFM BA DipStats DipProfEthics

Pro-Pare™	diabetes reversal	midinomics	chance or design?
tamaki sports academy	diabetes blog		genome topology
some thoughts			some opinions



molecular biology, lecture one

These next two lectures introduce some key ideas in cell biology, but the real question in a course such as this is, how did these things evolve? In this lecture our focus is on the eukaryotic cell. In the next our focus is on the regulation of gene expression.

The trick, in this lecture, is to understand the evolution of the cell from the first imperfectly reproducing molecule, as a series of small changes each of which has a reproductive advantage. It is only fair to say that no one has ever come close to creating a cell from lengths of DNA or RNA, and the proposed sequence of events have very little, if any, empirical support.

Indeed, as Darwinians can give no credible, tested account of the evolution of the eukaryotic cell they are accused of believing in this as a matter of faith. The response is, as it must be, we are working on this and we will find an explanation.

cell anatomy

this image is from the wallrain.com website

organelles

nucleus and nuclear membrane

In Archaea and bacteria, single celled organisms without a nucleus, genes are 'always on'. In eukaryote cells genes are not always on. Our assumption is that the nucleus has a role in this.

What does a cell nucleus do? Three things

• it maintains, through the nuclear membrane a local intranuclear environment that is physically different from that of the cytoplasm.
• it contains most of the DNA as chromosomes
• it contains the nucleolus,the most prominent structure in the eukaryotic nucleus under the light microscope. This is the site of rRNA transcription and processing and of ribosome assembly.

nucleolus

The nucleolus is a structure in the nucleus involved in the construction of ribosomes

chromosomes

A chromosome is actually two complementary strings of DNA. DNA consists of a repeating pattern of to which is attached, at regular intervals a molecule called a nucleotide or base. DNA hosts four different nucleotides A,T,C,and G and if the nucleotide sequence of one string of DNA is known the nucleotide sequence of the complementary string can be deduced. This is because nucleotides

In an animal or plant cell chromosomes are found in pairs. There are two examples of ‘chromosome 1’ and of every other chromosome, and each DNA string of each example is made up of a different sequence of bases.

cytoplasm

mitochondrion

centrioles

ribosome

smooth endoplasmic reticulum

rough endoplasmic reticulum

golgi vesicles

lysosome

microtubules

pinocytotic vesicle

cell (plasma) membrane

readings