Some of this stuff, you'll get a better explanation for and more in depth understanding of the further along in your studies you get. For instance with the walking, you'll learn later in high level biochemistry or cellular biology classes about the structure of http://en.wikipedia.org/wiki/Dynein" and other ATP-dependent motor proteins (like myosin) and how they "cock", "release" and "lever" forward.
This is an incredibly in depth subject, so I think it would be best (for your own sake) to learn it when the time is appropriate in your formal education and not over a forum (which is somewhat of a daunting task having people trying to explain something so complex to you over the internet).
Aside from that, to supplement your understanding and preview the [STRIKE]horrifying[/STRIKE] complex depth of knowledge to come, I'd honestly take a peek at some wiki pages on the subject. While it certainly isn't an academic standard, there are good articles, well written by people in the field nevertheless. Of course, use that as a spring board and just a way to help augment your formal studies (your textbooks, syllabus, class notes etc) and not the primary source of your information.
Stephen1993 said:
well i have studied the stuff before but now i would like to ask some questions that i don't get before
Steps in endosymbiotic theory
"would be the engulfing of a photosynthetic prokaryote (cyanobacterium), the precursor of the plastids including the chloroplasts."
what does the word "precursor" used in this context?
Like
mitochondria, chloroplasts were very, very likely at one time a free living organism. Who, again like
mitochondria and possibly some other organelles, traded off a free living life for one of a symbiotic-dependence. "Precursor" then, is simply referring to those prokaryotic ancestors of modern chloroplasts.
Stephen1993 said:
another one
"A mutation can occur either within the protein-encoding region of a gene, or in a non-coding sequence. If a mutation occurs within a gene, it can change the gene from one form to a new form. However it remains the same gene."
firstly which is slightly out of this topic: i thought the coding part of the DNA are genes and the non-coding parts are not genes. so how come in the paragraph above that there is coding and non-coding part of the gene?
secondly what does the last sentence mean?
thank you
The "idea" of a gene has changed over time. It used to be thought that 1 gene=1 protein in neat little ratios. Turns out, that biology is much messier than that. Most of our DNA doesn't code for proteins, heck most of a "gene" doesn't code for a protein. Large sums of it is given over toward regulatory regions, which bind inducers and suppressors and activators and modify the structure for access via replication/transcription machinery, etc.
Like Mish points out then, this is how alleles or gene "flavors" are made. A loci is a spot on a chromosome that is occupied by a gene. A change in that gene (either coding or non-coding regions) doesn't change the genes "address" on the chromosome. Thus, the mutation can make a new "flavor" (read: allele) of gene, but it isn't moving the gene itself (don't fret though, once you wrap your head around all that--They'll tell you that some types of mutations
do changes a gene's "address"
, don't you love learning?).