CHROMOSOMES8-1

DNAFound in NUCLEUS

Carries the genetic code

http://web.jjay.cuny.edu/~acarpi/NSC/12-dna.htm

http://encarta.msn.com/media_461516495/Nucleus_of_a_Cell.html

NUCLEIC ACIDS are built from subunits called

____________________

Image by: Riedell

Changing the _____________and _______________produces different subunits

sugar

nitrogen base

5 NITROGEN BASES

_____________= A

_____________ = G

_____________ = C

______________ = T (only in DNA)

______________= U (only in RNA)

ADENINEGUANINECYTOSINETHYMINEURACIL

DNA molecule forms a HELIXor “twisted ladder”

A on one strand always bonds with T opposite it

G on one strand always bonds with C opposite it

Image from: http://evolution.berkeley.edu/evosite/evo101/images/dna_bases.gif

SPREAD OUT INNON-DIVIDING CELLS

SCRUNCHED UPIN DIVIDINGCELLS

DNA CAN BE:

PROTEINS that wrap up DNA

are called __________________

http://biology.kenyon.edu/courses/biol114/Chap01/chrom_struct.html

PROTEINS

Proteins- Combine with DNA to make chromosomes

 Image from: http://employees.csbsju.edu/hjakubowski/classes/ch331/dna/chromosome.gif

Proteins that control the activity of genes are called ________________

http://www.blc.arizona.edu/courses/181summer/14.html

Cells turn genes on or off as needed (part of differentiation)

Example: Genes for making digestive enzymes are turned off in brain cells

Genes for making neurotransmitters are turned on

NON-HISTONES are the “on-off” switches for genes

CELL DIVISION GENES

Some cells divide frequently(some human skin cells divide once/hour)

Some cells divide occasionally (liver cells divide about once/year)

Some cells don’t divide once they form (nerve cells)

Cancer cells have lost control of their cell division genes

Cancer cells• Don’t stop dividing• Like a “car with no brakes”• Can spread to new places

(METASTASIS)

• ______________ are substances that can damage DNA

Ex: Radiation, cigarette smoke, chemicals in environment

DNA in PROKARYOTES

• BACTERIAL DNA is CIRCULAR

• HAVE ONE CHROMOSOME

• ATTACHED TO CELL MEMBRANE

http://www.origin-life.gr.jp/3202/3202121/fig6.jpg

DNA in EUKARYOTES(Plants & Animals)

• DNA is ROD-SHAPED CHROMOSOMES

• MANY PAIRS

• FOUND IN NUCLEUS

http://cellbio.utmb.edu/cellbio/chrom2.jpg

Chromosome structure• ___________________

2 identical arms

• __________________

constricted area holds chromatids together

•__________________ PAIR

2 of each chromosome(one from mom; one from dad)

HOMOLOGOUS CHROMOSOMES

http://arnica.csustan.edu/biol3020/cell_division/cell_division.htm

• SAME SIZE

• SAME SHAPE

• CARRY GENES for the SAME TRAITS

(Don’t have to have the SAME CHOICES)

CHROMOSOME NUMBERS• Each species has a

characteristic number of chromosomes

• HUMANS have 46 chromosomes (23 pairs)

You can’t judge a critter by its chromosomes

This critter has54 chromosomes

Corn has 10 pair of chromosomes

Snails have 18 pairs of

chromosomes

A mouse has 40 chromosomes

CHROMOSOME NUMBER DOESN’T CORRESPOND TO SIZE OF ORGANISM

Big animals DON’T have more chromosomes than small animals!

http://www.ocean.udel.edu/extreme2004/genomics/images/chromosomes.gif

• Chromosomes that determine the sex of an organism = _________________________

• All other chromosomes = _________________

Humans have two sex chromosomes

And _____ autosomes

A _____________is a picture of an organism’s chromosomes

A KARYOTYPE can tell the sex of an organism

In humans XY is a male

In humans XX is a female

Guess who?

XY

Karyotypes can also show some genetic problems

http://members.tripod.com/~yenial/chromosome.html

Eric has Down’s Syndrome

1 in 750 births

Has extra #21 chromosome

Mental retardation

DIPLOID & HAPLOID Some cells have 2 copies of each

chromosome = _______________

(one from mom; one from dad)

• All BODY cells are diploid

Image from: http://www.ncu.edu.tw/~ls/graph/faculty_pictures/whole_time/SLC/SLC_lab-1.jpg

DIPLOID & HAPLOID

Some cells have only one copy of each chromosome = ____________________

All sperm and egg cells are haploid

EGG + SPERM

If egg and sperm had same number of chromosomes as other body cells …. baby would have too many chromosomes!

http://www.angelbabygifts.com/

CELL DIVISION8-2

Mitosis and Meiosis

CELL DIVISION in PROKARYOTES

Bacteria

reproduce

using__________________

•DNA is copied•Cell wall forms•Cell splits into two new cells

http://www.tnau.ac.in/notesbscag/agm/UGMicro/AGM151_201/theory_files/image156.jpg

CELL DIVISION IN

EUKARYOTES

__________ OR __________

MITOSIS• Makes ____ cells

identical to parent cell

• Makes _____ cells

• Makes _______ cells

• Used to _____________& ____________________________________

MEIOSIS• Makes ____ cells with

different DNA

• Makes _____ cells

• Makes ____________

• Used ______________

CELL CYCLE

G0

CELL CYCLE

cells alive cell cycle

CELL CYCLEINTERPHASE – non dividing phase

G1- Grow bigger Cell is “doing its job”

DNA is spread out as chromatin

S - Synthesis (copy DNA)

G2- Grow bigger, make organelles & molecules needed for cell division

CELL CYCLEMITOSIS – Cell division

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

G0 – cell stops dividing (Ex: nerve cell)

INTERPHASE (G1 - S - G2)

In between divisionsCells are in this phase most of the timeCan see nucleus DNA spread out as chromatin

Can’t see chromosomes DNA gets copied

Cell gets ready to divide

PROPHASE1st dividing phase

Spindle fibers form & attach chromosomes

Nuclear membrane & nucleolus disappear

DNA scrunches into chromosomes

Centrosomes containing centrioles appear & move to poles

METAPHASE

Chromosomes line up in ___________

ANAPHASE

Centrioles pull chromosomes ________

TELOPHASE (reverse prophase steps)See ______ nucleiNuclear membrane & nucleolus return

Chromosomes spread out as chromatinCentrioles disappear

Spindle fibers disappear

CYTOKINESISCytoplasm splits into 2 cells

ANIMAL CELLS pinch cytoplasm in two with a ______________________

CYTOKINESISCytoplasm splits into 2 cells

PLANT CELLS can’t pinch because they have a ______________

Separate cytoplasm by growing a _________________ down the middle.

CELL CYCLE

G0