wk10, looking ahead to wk11

The Cell Cycle

In week 10 we discussed the phases of the Cell Cycle, and spent extra time on cell division, including mitosis.

First in the Cell Cycle our cells grow (G1 phase).  Then they replicate their DNA (S phase).  Then they grow some more, do checks for accuracy, and get ready for mitosis (G2 phase). These three phases together are known as interphase.

Once the cells are done with interphase they enter M phase, also known as cell division.

Ok, so we aren't really doing mathematical division.  It is actually more like multiplication, since we start with one and end up with two.  

Cell division is comprised of two parts - mitosis and cytokinesis. Mitosis is itself comprised of four phases - remember PMAT? Prophase, Metaphase, Anaphase, and Telophase.  Each step is important for orderly production of two identical daughter cells.

Looking Ahead to wk11

Cell division using mitosis is important to create additional somatic (body) cells for growth, or for replacement if the cell is damaged or destroyed. All of this happens within the same organisms.  Some organisms use very similar processes to create duplicate organisms. Examples of this are budding and binary fission. Binary fission is the common mode of reproduction in bacteria - each bacteria (made up of a single cell, but still a distinct organisms) makes a duplicate of itself to create additional bacterial organisms. These types of reproduction, where the new organism is an exact genetic copy of the parent organism, are called asexual reproduction.

Humans and a great many other complex organisms, use a different method of reproduction known as sexual reproduction, where two incomplete sets of DNA from two parent organisms combine to make a genetically unique offspring. In order to produce the needed special cells (called sex cells or gametes), which have only half of the genetic information (haploid), there is a similar but different process to mitosis and it's called meiosis.

So why go through this extra effort of creating cells that have half the genetic information (haploid) just to combine them with another haploid cell from a new organism with complete genetic information (diploid)? Why not just use asexual reproduction like starfish and bacteria and make little clones of ourselves instead? There are several reasons, but the big one is this: genetic variation.    We will take more about genetic variation in wk12 and when we discuss evolution, but for now know that genetic variation is what gives individual organisms of the same species variety - say in birds different feather coloring, different beak shape, different body size, different songs, etc.  It is this variety that allows the species as a whole to adapt to the environment.

Here are the readings and videos/resources for this week.  Don't forget to keep working on your vocabulary.

11 Sexual vs Asexual reproduction, ploidy, meiosis

RSO Ch. 9 Meiosis Divides by Two and Makes You

LOE Ch 12 Intro-Review

CK12 BC 2.36-2.40

CK12 LSC 2.20-2.22

Chromosome Numbers in Mitosis - transition, Amoeba sisters cover the number of chromosomes at different stages in mitosis and meiosis Meiosis The Great Divide - transition, Amoeba sisters do an overview of meiosis and gamete formation Meisosis Square Dance - both, Ok, this is funny! But it can also be a good way to remember the phases of meiosis, and what happens at each.  You can use this worksheet that has the lyrics and  questions to clarify the steps Sexual vs Asexual Reproduction - both, this is an interactive to quiz your understanding of what organisms use sexual reproduction, asexual reproduction, or both. Meiosis - scholar, Crash Course covering meiosis and the production of gamete cells

wk9, looking ahead to wk10

First off, my apologies to you that I wasn't able to be in class last week.  But thanks to teacher Christy and teacher Cindy for filling in!

I hope that you learned a lot in wk 9's readings, because there was definitely a lot to learn.  Some key points to remember:

• DNA is the molecule that contains our genetic information; it is very long; each molecule of DNA is organized in a tightly wound manner into chromosomes
• During DNA replication a complete copy of each chromosome is made
• RNA is a single-stranded nucleotide made directly from DNA; there three types of RNA including messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA)
• RNA is used for transcription (the copying individual genes from the DNA code and moving those copies outside the nucleus) and translation (the forming of polypeptide proteins according to "code")
• Genes are distinct segments of DNA in the chromosome which code for a single protein/protein complex

Looking ahead to wk 10

The wk10 reading and videos are related to wk9.  The replication of DNA is an important part what is known as the Cell Cycle.  This is basically the life history of a cell - it grows, replicates its DNA, grows some more and checks for mistakes, splits in two, and we start over again.

Each phase and step in the process serves a purpose.  Some cells go through the entire cell cycle at a very rapid pace.  Other cells move through it slowly.  Still other cells, such as neurons, leave the cycle after the G1 phase and go to what is known as G0.  These cells spend so much time functioning they don't have time to replicate.

So finish this week's reading, and check out the additional videos.  Don't forget about your vocabulary list, too.

10 Cell Division, Cell Cycle, Chromosomes, Mitosis, Cytokinesis

RSO Ch. 8 Mitosis

LOE Ch 9 Intro-Review

CK12 BC 2.32-2.35

CK12 LSC 2.17-2.19

Cell Cycle and Mitosis - transition, Amoeba sisters talk about cell cycle and growth. Including cancer Mitosis: Amazing - transition, Amoeba sisters cover mitosis and the role of chromosomes Mitosis Dance - both, humorous mitosis dance by college genetics class Phases of Mitosis - Scholar, a well-done explanation by Bozeman Science looking at all the changes in each phase of mitosis Mitosis - scholar, Crash Course video on mitosis. Sometimes watching two videos on the same thing can help cement the ideas.

Wk 8, Looking Ahead to Wk 9

Respiration

This week in lab we reviewed respiration, and how it is like the mirror opposite of photosynthesis.

We also walked through a lab procedure, discussing how to set up an experiment with a hypothesis, independent variable, dependent variable, controlled variables, experimental treatments, controlled treatments, and alternative hypotheses.  We then attempted to observe respiration of bread yeast indirectly by the bubbles of carbon dioxide it produced.  Sadly, because of poorly controlled variables (temperature) and lack of sufficient time we had very unimpressive results.

Sigh. That happens in science though, more often than you might think.  But you probably didn't realize that because you only hear about the exciting results.  Why? Because we don't publish results that are inconclusive.  Therefore, I am scratching this first lab write up.  There's not enough data to write up on!

Don't feel too sad about it though, we still have 4 more labs this year. And I still think the time walking through the parts of an experiment was time well spent.

Looking ahead to wk 9 (and beyond)

The coming weeks are very information heavy.  We will spend our time in class reinforcing ideas from the reading, but if you don't read you're going to be lost.

Wk 9 will cover DNA, DNA replication, RNA, transcription and translation, and the organizational relationship between DNA-genes-chromosomes.  

There is way too much for me to do a short intro, so please do your reading and be mindful of the following:

• DNA is an incredibly long molecule holding the "code" for living organisms
• Each DNA molecule is coiled and wound tightly into a structure called a chromosome
• Distinct segments of DNA on a chromosome, and is the molecular unit of inheritance
• The central dogma of molecular biology: DNA is transcribed into RNA which is translated into proteins

*In your reading and watching videos be careful not to confuse DNA replication with transcription to RNA*

The wk 9 videos are organized so there is a series for the transition students (Amoeba Sisters) and a series for scholar students (the Australian guy).  There are also three videos to clarify some basic points.  I know there are a lot of video links, but as I said in the beginning this is a lot of material to cover and can be confusing to understand.  Use the videos to solidify the concepts from your reading.  The last two links are for interactives on DNA replication and transcription and translation.

Don't forget to keep working on your vocabulary lists!

9 DNA Structure and function, DNA replication, DNA-genes-chromosomes relationship, RNA structure and function, Protein synthesis (transcription and translation)	RSO Ch. 7 The Message	LOE Ch. 10 Intro-10.3	CK12 BC 2.34 And 4.1-4.7	CK12 LSC 3.1-3.6	DNA Structure and Function - Transition, Amoeba sisters  video about DNA and what it does DNA Replication - Transition, Amoeba sisters video about DNA replication Why RNA is Just as Cool as DNA? - Transition, Amoeba sisters video about the important role the types of RNA plays in  protein synthesis Protein Synthesis and the Lean, Mean, Ribosome Machine - Transition, Amoeba sisters video on how proteins are synthesized What is DNA and How Does it Work? -  both, general overview of DNA  from Stated Clearly What is a gene? - both, general overview of genes from Stated Clearly From DNA to Protein - both, highlights of the process of protein formation from the DNA code What is DNA? - Scholar, the first in a series of videos from our Aussie friend on DNA, RNA, genes, chromosomes, how this message codes for and creates proteins. DNA Replication - Scholar What is RNA - Scholar DNA, Chromosomes, and Genes - Scholar The Genetic Code - Scholar Protein Synthesis I (Transcription) - Scholar Protein Synthesis II (Translation) - Scholar Interactive on building a DNA molecule Interactive on transcription and translation
10 Cell Division, Cell Cycle, Chromosomes, Mitosis, Cytokinesis	RSO Ch. 8 Mitosis	LOE Ch. 9 Intro-Review	CK12 BC 2.32-2.35	CK12 LSC 2.17-2.19
Thanksgiving Break	Have fun!	Eat proteins (turkey)	Eat carbohydrates (pie)	Eat fats (gravy)
11 Sexual vs Asexual reproduction, ploidy, meiosis	RSO Ch. 9 Meiosis Divides by Two and Makes You	LOE Ch. 12 Intro-Review	CK12 BC 2.36-2.40	CK12 LSC 2.20-2.22
12 Genetics, Inheritance *Second Mini Project - Qwotekutesnute*	RSO Ch. 10 Your Inheritance	LOE Ch. 11 Intro-Review	CK12 BC 3.1-3.15	CK12 LSC 3.8-3.14