Day 9 September 21 Chapter 5 Scribd

8/4/2019 Day 9 September 21 Chapter 5 Scribd

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Day 9 September 21 Chapter 5

I will ask several clicker questions at

the beginningGET READY PLEASE!


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A chicken dinosaur? Scientists

discover what the bird might

have look liked in prehistoric

times


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Continuity and varietyLectures by Mark Manteuffel, St. Louis Community College; Clicker Questions by Kristen Curran, University of Wisconsin-Whitewater

Chapter 6: Chromosomes and Cell Division


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Bladder Cancer cells


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6.1 Immortal cells can spell

trouble: cell division insickness and health.

Once you are fully grown, do you have just one set of cells

that live as long as you do?


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Telomeres

The telomere is like aprotective cap at theend of the DNA.

Every time a cell

divides, the telomeregets a bit shorter.

(Like a cars odometer)


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At birth, the

telomeres inmost human cells

are long enough

to support about

50 cell divisions

Is there a Fountain of Youth?


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Cancer

These are cells

that rebuild

theirtelomeres

after each cell

division,

restoring theprotective cap,

never stop

dividing


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Cancer cells are thosewhich have forgotten

how to die.Harold Pinter


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6.2 Some chromosomes are

circular, others are linear.

prokaryote eukaryote


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6.3 Prokaryotes divideby binary fission.


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6.4 A time for everything: the cell cycle.


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6.5 Cell division is preceded by

replication.Persistence and propagation


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Replication

The process of DNA duplication


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Complementarity

the characteristic that in the double-stranded DNA molecule the base on onestrand always has the same pairing-

partner (called the complementarybase) on the other strand


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Complementarity

Every A (adenine) pairs with T(thymine) and vice-versa.

Every G (guanine) pairs with C(cytosine) and vice-versa.


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Mistakes sometimes occur

when DNA duplicates itself?

Why might that be a goodthing?


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Mutation

A variety of errors can occur duringreplication.

Several DNA repair processes occur afterreplication.

If an error remains, however, thesequences in a replicated DNA molecule(including the genes) can be differentfrom those in the parent molecule.


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6.6 Most cells are not immortal:mitosis generates replacements.

What isdust?

Why is it yourfault?


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Mitosis has just one purpose:

To enable cells to generate new,genetically identical cells.

There are two different reasons for thisneed:

1. Growth2. Replacement


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Mitosis

The number of (somatic) cells that mustbe replaced by mitosis every day is huge.

The rate at which mitosis occurs variesdramatically.


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6.7 Overview

Mitosis leads to duplicate cells.

Parent cells daughter cells


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Preparation forMitosis: The

ChromosomesReplicate


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Animal chromosomes are linear.

So why do they look like the letter

X in pictures?


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Sister Chromatids

A chromosome and its identical replicatedcopy, joined at the centromere.


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Tumor Growth

unregulatedcell division


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Cancer cells haveseveral features

that distinguishthem from normalcells, including


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Benign and Malignant Tumors


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Why is the treatment for cancer oftenconsidered as bad as the disease?


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6.10 Sexualreproduction

requires specialcells made bymeiosis.


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Meiosis

gametes

diploid

haploid

maintains a stable genome size in aspecies


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Meiosis achieves

more than just areduction in theamount of

genetic materialin gametes.

You have twocopies of everygene!


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Meiosis has two important features:

1. It reduces the amount of geneticmaterial in gametes.

2. It produces gametes that all differ fromeach other with respect to thecombinations of alleles they carry.


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6.11 Sperm and egg are producedby meiosis: the details, step-by-step.

Mitosis occurs almosteverywhere in an animals body.

Meiosis only occurs in one place.Where?

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Day 9 September 21 Chapter 5 Scribd