Main Principles

• Prokaryotes, eukaryotes• Each organism starts from one cell• All organisms are made of cells• Each cell of each organism has the same

number of chromosomes• Each species has a certain number of

chromosomes

Chromosome numbers in some plants Plant Species #Arabidopsis thaliana (diploid) 10Rye (diploid) 14Maize (diploid) 20Einkorn wheat (diploid) 14Durum wheat (tetraploid) 28Bread wheat(hexaploid) 42Potato (tetraploid) 48Cultivated tobacco (diploid) 48Adder's Tongue Fern (diploid) approx 1,440

Chromosome numbers (2n) in some animals Species # Species #Common fruit fly 8 Guinea Pig 64Dove 16 Garden snail 54Earthworm Octodrilus complanatus 36 Tibetan fox 36Domestic cat 38 Domestic pig 38Lab mouse 40 Lab rat 42Rabbit 44 Syrian hamster 44Hare 46 Human 46

Gorillas, Chimpanzees 48 Domestic sheep 54

Elephants 56 Cow 60Donkey 62 Horse 64Dog 78

Goldfish 100-104

Eukaryotic Chromosomes

• Haploid cell – n (number of chromosomes)• Diploid cell – 2n (number of chromosomes)• Genome• Homologous chromosomes• Autosomes, sex chromosomes• Karyotype

www.iknow.net/cell_div_education.html

sisterchromatids

duplicatedchromosome(2 DNA double helices)

Cell Cycle

• Stages of cell cycle• G1• G0• S• G2• All together -

interphase

• Stages of mitosis:• Prophase• Metaphase• Anaphase• Telophase• Cytokinesis

Mitosis

• Mitosis is a cellular division for _________________________________

• One cell after mitotic division produces ___________________________________

• The number of chromosomes is ___________________________________

Mitosis

• Chromosomes duplicate in interphase, forming sister chromatids

• Phases of mitosis:–

Interphase• S phase -chromosomes duplicate,

___________________________________• Microtubule organizing centers (MTOCs) –

_____________________________________• Centrosome –

_______________________________________________________________________________

G2 of Interphase

• - nucleus __________________________ - one or more nucleoli present - two pairs of centrioles ________________________________ - chromosomes have already duplicated __________________________________

Nucleolus

• ______________________________________________• Ribosomal or rDNA is a set of tandemly-repeated genes

coding for preribosomal RNA, serves as its foundation.• These segments of the chromosomes are called nucleolus

organizer regions or NORs.

Prophase

- chromatin coils & folds into _______________________________

- each chromosome consists of two identical __________________________________ - spindle forms consisting of microtubules - centrosomes ______________________

Prophase

• Fragmentation of many intracellular organelles except mitochondria and chloroplasts

• Nuclear membrane breaks into small vesicles• Microtubules formed in the cytoplasm invade the

nuclear space• Kinetochores – proteinaceous structures

associated with the centromeres

Prometaphase

• - nuclear membrane fragments - microtubules _________________________________ - spindle fibers extend from _______________________________ - bundles of microtubules (kinetochore microtubules) attach & put chromosomes in motion

Metaphase

• chromosomes move to ___________________________________

• identical chromatids are attached to kinetochore fibers radiating from opposite ends ______________________________

Anaphase

• - sister chromatids separate and are considered _________________________- spindle apparatus starts moving separate chromosomes to _____________________ - poles of cell move farther apart slightly elongating the cell

Telophase

• daughter nuclei begin to form __________________________________

• nuclear envelopes form• nucleoli reappear• chromatin uncoils and chromosomes

become ___________________________

http://www.bio.davidson.edu/misc/movies/CarMitosis.mov

http://www.bio.davidson.edu/misc/movies/mitosisnewt.mov – this one and nexthttp://www.bio.davidson.edu/misc/movies/mitosislily.mov

Vocabulary

• Prokaryotes, eukaryotes• Haploid, diploid• Chromosomes, chromosomal number• Karyotype• Homologous chromosomes• Sister chromatids

Vocabulary

• Locus (loci)• Gene, allele• Biparental inheritance – one from mom, one

from dad• Autosomes, sex-determining chromosomes• Somatic cells, germ cells, gametes, zygotes• Karyokinesis, cytokinesis