ch.12 - mitosis.docx

5 Pages
67 Views
Unlock Document

Department
Biological Sciences
Course
BIOSC 0150
Professor
Christine Dahlin- Universityof Pittsburgh Johnstown
Semester
Spring

Description
1 General biology 1 Chapter 12 – Cell division: Mitosis Cell division – reproduction of cells - Pass genetic material to cellular offspring Prokaryotes – produce entire other organisms Eukaryotes – develop from a single cell Cell cycle terms - Genome – all the DNA (genetic info) in a cell o Packaged into chromosomes  Long DNA molecules coiled around protein  Each chromosome – hundreds to thousand genes  DNA + protein = chromatin - Diffuse chromatin – chromatin coils up after dividing - Sister chromatids – chromosome coiled up tight; dyads – duplicated chromosome How do we get new cells? - Mitosis & cytokinesis – creates somatic cells (nonreproductive cell) o Full set of chromosomes - Meiosis – creates gametes (reproductive cells) o Have only ½ of chromosomes per cell Specific differences - Eukaryotes have set numbers of chromosomes - Human somatic cells – 46 chromosomes - Human gametic (reproductive) cells – 23 chromosomes - Varies in species: chimpanzee (48), hedgehogs (90), cabbage plants (18) What can cells do? - “Hang out” and do their thing - Prepare to divide then divide (“cycling”) - Also die by apoptosis = suicide How does cell decide what to do? - Monitor environment – intra and extracellular - Cell asks – whether or not they are ready to divide? o Where are signals to divide? - Division occurs in response to a signal Ex/ growth factor o Binds to receptor in membrane o And enter cells so then cell commits to dividing - Interphase – G1 (or 1 gap phase) in response to a signal to divide o S (DNA synthesis) – cell prepares to divide o G – 2ell prepares to divide o Mitotic (M phase) – include mitosis and cytokinesis where cell finally divides - Mitosis – cell division o Have exact copies of DNA and split in half o Growth or repair/replacement 2 General biology 1 Chapter 12 – Cell division: Mitosis Overview - Preparation – cell decides to divide - Replicate the DNA – copy all chromosomes - Mitosis – segregate the chromosomes and move them to the daughter cells (new cells) - Cytokinesis – when a cell has physically splits apart into 2 daughter cells (and cytoplasm) Cell cycle 1. Interphase – prepare to divide o Make protein, organelles and replicate DNA o Division of mitosis and cytokinesis - Subphases of interphase are G1, S, G2 phase a. G (1 gap) – “resting”  Make decision to divide or not b. S (synthesis phase) – DNA replication c. G –2preparation for mitosis Orderly/regulated progression - G1 – grow and deciding whether or not to divide - S (synthesis) – DNA replication o Making exact copies of cell: duplicates - G2 – more growing of cell Chromosomes separate during mitosis - Monad (an unreplicated chromosome) get duplicate  occurs in G1 phase - Sister chromatids – monad duplicate into 2 identical joined chromosome o A duplicated chromosome that is condensed - Then sister chromatids get separate into 2 chromosomes that contain an original chromosome and a replicated chromosome pairs  occurs in M phase Centromere – a DNA sequence at the “constriction” of a chromosome When and why cell divide? - Cell control system – molecules that trigger and coordinate key events - Human skin cells: divide frequently - Live cells: divide as needed i.e – wound repair - Some specialized cells never divide once fully formed! Ex/ nerve cells Cell cycle transitions: - Controlled by Cdks and cyclins - Cycle-dependent kinase (Cdk) o Enzyme – phosphorylates (transfer phosphate group from ATP) o Activates or inactivates proteins o Cell cycle progress when Cdk is active Cdks – always present in cell but not always active - Only active when cyclins bind to - BUT cyclins NOT always present 3 General biology 1 Chapter 12 – Cell division: Mitosis - Levels “cycle” is high, low, high, low, … - Based on gene expression and degradation Cyclin – activating molecule (a protein) that fluctuate cell concentration from its cyclically - Activates CDK phosphorylate proteins - Increase during S and G2 phase - High cycle means cell ready to divide Ex – MDK: cyclin-CDK complex which requires high cyclin! When there is enough MDF (M phase promoting factor), mitosis begins Regulation of cell cycle at G2 complex by Cdk and cyclin - An active kinase include cyclin-Cdk complex - Several cyclin-Cdk protein complexes regulate all stages of cell cycle Cell cycle checkpoint - Stop cell cycle when there is a problem o Survey cell – monitor internal and external signal
More Less

Related notes for BIOSC 0150

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit