1. Cell division and DNA 1. Parent cell 2. DNA Replication 3. Daughter
Cells

2. General idea:
As organisms grow their cells must multiply
‘Parent’ cells give rise to ‘_______’ cells
DNA inside parent cells must be duplicated
One copy for each daughter cell
First, need to understand chromosomes & DNA

3. Chromosomes: coiled strands of DNA
Number varies among species
__ in humans, __ HOMOLOGOUS PAIRS
Each pair=1 from ___ + 1 from ___
Fruit fly
Human karyotype
One homologous pair
Muntjac deer
From father
From mother
Rat

4. Chromosomes can occur singly or in duplicate
Called a chromosome in ______ case
Unreplicated
chromosome
________
chromosome
________
chromosomes
Sister ________
(identical)
centromere

5. Two types of cell division:
MITOSIS: creation of ________ cells
For _______ and replacement
MEIOSIS: creation of ____ cells
Topic of our next lecture
Cell division

6. Mitosis is a part of the overall Cell Cycle
Cell division
Growth phases
not addressed
in later slides
Cell division

7. (uncoiled chromosomes)
Interphase
- Preparation for _____ cell division
- DNA ________, seen as ________ (cloudy)
- Centrioles clustered together
Nucleus
Cell membrane
Chromatin
(uncoiled chromosomes)
Centrioles
Sketch 1
Cell division > mitosis > interphase

8. X x Mitosis is studied in phases Early Prophase of Mitosis Sketch 2
- Chromatin condenses into ___________ chromosomes
- Centrioles move apart
- Spindle fibers extend toward _________________
This organism has only _ pairs of chromosomes X x
Spindle
fibers
____________ pair
of chromosomes
(one from mother, another from father)
One _______ chromosome
(a pair of sister
chromatids)
Sketch 2
Cell division > mitosis > prophase

9. X X x x Late Prophase of mitosis: - Nuclear envelope __________
- Spindle fibers connect to _____________ X x
centromere X x
Sketch 3
Cell division > mitosis > prophase

10. X X x x Metaphase: Spindle fibers pull chromosomes to _____________
metaphase plate
Sketch 4
Cell division > mitosis > metaphase

11.         Anaphase: - Sister chromatids get separated
Become ________ chromosomes        
Daughter
chromosome
Sketch 5
Cell division > mitosis > anaphase

12.         5) Telophase: Two nuclear membranes develop
Cytoplasm becomes divided    
Daughter cells are ________ identical    
Sketch 6
Cell division > mitosis > telophase

13. In animals, ___________________separates daughter cells
Telophase differs in plant & animal cells
In animals, ___________________separates daughter cells
In plants, a _________ develops between cells
Cell division > mitosis > telophase

14. DNA = Deoxyribonucleic Acid
DNA molecule
Chromosome
histone proteins
one base pair
Human DNA:
~ 2 m (~6 ft) long – in each cell!
~ 20,000-25,000 genes (genetic traits)
~ 3 billion pairs of monomers (___________)
DNA

15. Genome maps
A record of all base pairs & ________ of a species
E.g., Human chromosome #2:
Known genes:

16. The monomers of DNA are ___________ Nucleotides have 3 parts:
Nitrogenous
____
Phosphate
_____
Deoxyribose
_____
Adenine
Nitrogenous base can be 1 of 4 types:
Guanine, Cytosine, Adenine or Thymine
DNA > monomers

17. Nucleotides are linked by _____________ backbone
Phosphates
Bases
Sugars P
Cytosine S P
Adenine S P S
Guanine
DNA > sugar-phosphate backbone

18. DNA is a ‘double-spiral’ molecule A ladder-like “___________”
Variation in sequence of ________ produces variation in ‘genetic code’
E.g., the codes AGTA and GATA code for different information
DNA is a ‘double-spiral’ molecule
A ladder-like “___________”
Bonded pairs of
nitrogenous bases
Sugar-phosphate backbones
The double strand is twisted cork-screw-like
DNA > double helix

19. James Watson (American, 23) and Francis Crick (Brit, 35) won the 1953 Nobel Prize for describing the ____________ structure of DNA
Very short: move up to end of mitosis, make lecture 10 all meiosis
Introns & exons
DNA > double helix

20. DNA strands are held together by ________ bonds
Hydrogen
bonds
Only ___________ base pairs bond together
Complementary base pairs:
Adenine & Thymine (A-T); use __ hydrogen bonds
Cytosine & Guanine (C-G); use __hydrogen bonds
DNA > replication

21. DNA replication (during __________):
Chromosomes unravel, appear as cloudy ________
Helicase enzyme “_______” DNA strands
Breaks hydrogen bonds binding the strands
Creates a “replication _______” A C G T
Helicase A C G T
DNA > replication > unzipping

22. DNA Polymerases build new daughter strands
Attach _____________ nucleotides to each DNA strand A C G
DNA
polymerase T __ __ A C G T
DNA > replication > daughter strands

23. DNA POLYMERASES build new daughter strands
Attach complementary nucleotides to template A C G T A C G T
DNA > replication > daughter strands

24. A C G T A C G T
DNA > replication > daughter strands

25. Each with ½ ___ and ½ ___ DNA G T 2
daughter
DNAs A C G T
Identical
Each with ½ ___ and ½ ___ DNA
Ensures accurate replication of DNA for both new _______ cells
DNA > replication > daughter strands

26. Replication can not continue to ____ base pairs
________ are non-coding end-caps where shortening occurs
2nd DNA polymerase lags behind first
Leaves a bit of single-stranded DNA at ends
_______ chromosome with each replication
Become shorter with each replication – with ____
After telomeres become completely eroded:
- _____ genes become eroded
- genetic ______ occur