Cell Division Unit 11 What triggers division How

Cell Division Unit 11 • What triggers division? • How does division happen? • What can happen when division goes wrong?

Division as Reproduction. o In your body right now, there are trillions of cells, but you started out from just one cell. Where did all of those cells come from? You know a baby is much smaller than an adult – how does the smaller body of a baby grow into the larger body of an adult

Types of reproduction: Asexual Reproduction Sexual Reproduction

DNA and chromosomes When cells divide, the genetic material inside the nucleus must also divide. o Genes are segments of the DNA molecules that function to: 1) Act as a template formation of m. RNA strands used in protein synthesis. 2) Act as a unit of hereditary information to carry the genetic information from parent to offspring. o Genome _________________ o

DNA comes in various forms depending on the type of organism: 1) Prokaryotes (bacteria and Cyanobacteria) a) ____________________ and b) ____________________ o o 2) Eukaryotic cells have a larger genome. Genes are distributed on several pieces of DNA called _______________.

Prokaryotic Cell Cycle 20 min/cycle! o Part 1 - Growth and DNA replication o Part 2 - Binary Fission

Eukaryotic cells – 2 types of division o Mitosis – asexual reproduction - 1 round of division – identical offspring – somatic cells o Meiosis – sexual reproduction – two rounds of division - genetically distinct but similar offspring – gametes – genetic info reduced by half often called a REDUCTION DIVISON

Eukaryotic Cell Cycle differentiation

The form of DNA in Eukaryotic cells depends upon whether the cell is dividing or nondividing: Note: no matter which FORM – chromatinchromosomes-

Why would it be an advantage to have the DNA in the form of chromatin in a non-dividing cell? Why does the DNA condense into chromosomes before cell division?

Chromosomes : Telomeres Centromeres Two configurations of chromosomes: 1) Single arm chromosomes _________. 2) Double-arm chromosomes are made up of paired, genetically identical chromatids, called ______ are joined at the ________.

Chromosome Pairs: o o Each of your body cells has ______ total chromosomes which come in pairs. You have ______ pair. 22 of those pairs are very similar to each, with the same genes, and homologous chromosomes. These are ________ 1 of those pairs contains sex chromosomes. Female have 2 sex chromosomes that are homologous; or XX Males have X and Y, these are not homologous and contain different genes.

Karyotype Picture of the pairs of chromosomes in a human cell:

o Half of your chromosomes came from _______. o The other half is from _____________. o Chromosome pairs are called ___________ o _____________ (chromosome pairs) are given numbers based on microscopic characteristics. Homologous chromosomes have: o _____________________________________________ o _______________________

What is the chromosome pair or ________ for the #13 chromosome you received from your father? _______________ Human body cells contain both homologs of a homologous pair, and are considered to be diploid, or 2 n. o In humans, the diploid number is ______. Human sex cells contain only 1 homolog of the homologous pair, and are considered to be haploid. o In humans, the haploid number of chromosomes is _____. o

Chromosome Number Organism Diploid* number of Chromosomes in each cell. goldfish 94 chimpanzee 48 human _____ brown bat 44

The Cell Cycle: This continual cycle of cell division that produces genetically identical cells (clones) occurs in three phases: o interphase: ________________ o mitosis: __________________ o cytokinesis: ________________ What form is the genetic material in each phase of the cell cycle?

o At this exact moment, what phase of the cell cycle would most of your body cells be in? ______ Rate of Division: What about skin cells? Nerve cells? Bone cells?

Summary of Events in the Process of Mitosis and Cell Division: Begin with: ____ of pieces of chromatin DNA Replication Condense DNA Split Chromatids ____ replicated chromatin ______ double armed chromosome ______ single armed chromosome End with: _____ of pieces of chromatin per cell

PHASES OF THE CELL CYCLE: I. INTERPHASE _____________________________ o What types of processes might be taking place in a cell during interphase? __________________ o Is the cell shown below an animal or plant cell? o

o G 1 phase o S phase o G 2 phase

II. MITOSIS o Prophase

o Metaphase

o Anaphase

o Telophase

Cytokinesis CYTOKINESIS differs between plants and animals: 1) Furrow-in animal cell ______________ 2) Cell plate in plant cells ______________

Factors that affect the rate of division and the progression through the cell cycle. From the inside of the cell: 1. Type/species of organism 2. Type of cell: ex. skin, stomach, embryonic cells frequently divide while mature nerve, blood and muscle cells do not divide Both 1 and 2 are pre-programmed into the DNA of each organism. 3. Size of cell (SA/V ratio), nutrients available, and density of cells.

o Check of chromosome status- o presence or absence of CYLCIN – o Age of Cells:

From the outside: o Growth factors:

So what is cancer? It is: causes: