DNA AND CELL

REPLICATI

ON

DNA• Deoxyribonucleic acid• Sugar-phosphate “backbone”

with nucleotide “ladder steps”• Has 2 complementary strands

NUCLEOTIDES• 4 different nucleotides•A=adenine•T=thymine•C=cytosine•G=guanine• A always pairs with T• G always pairs with C• Called base pairs

CHROMOSOMES

• DNA is wound up and compacted to form chromosomes• Chromosomes are passed

from parent to offspring• You have 46 chromosomes,

23 from each parent

MUTATIONS

• A mutation is a change in the DNA• Can be good or bad• Can be caused by

pollutants, UV rays (sun), or occur naturally

ASSIGNMENT

• Make 2 models of DNA• Include 10 base pairs• Make a key for your base

pairs• Be sure to pair up

nucleotides correctly!

MITOSIS• Cell replication in asexual

reproduction and cell duplication

• DNA of parent and offspring is identical

MITOSIS

Goal-One copy of the DNA is distributed into each of the 2 daughter cells

In order to reach goal, DNA must replicate itself first!

STEPS OF MITOSIS

• Prophase- DNA condenses to form chromosomes• Metaphase- Chromosomes line up

across center of cell• Anaphase- Chromosomes separate

and move to opposite ends of cell• Telophase- Nuclear envelopes form

around DNA, 2 new cells are created

ACTIVITY

• Draw a line down the back of your paper from yesterday.

• You are going to draw a cell going through all the steps of mitosis.

• Use the diagram on pg C58 to help you.

MEIOSIS

GOAL- Make 4 copies of cells to be used in sexual reproduction.

Each daughter cell will have ½ the DNA of the parent.

MEIOSIS

First the DNA duplicates itself

Next it goes through mitosis to create 2 daughter cells

Finally, each cell goes through mitosis a second time

Total cells=4Total DNA=1/2

GENETIC DISORDERS

• Can be caused by mistakes during meiosis

• Mutations can occur by crossing over of chromosomes

GENETIC DISORDERS• Klinefelter Syndrome-males have XXY

chromosomes• Turner Syndrome-females only have one X• Down Syndrome- extra copy of

chromosome 21• Sickle Cell Disease- recessive gene

chromosome 11• Hemophilia- recessive x-linked gene

LIGERS• Lion and tiger mixed together• Half of its DNA is from lion, half

from tiger• Has traits of both animals• Does not occur in nature

ACTIVITY• After you have made your model of

meiosis, you need to create your own hybrid!

• Draw a picture of what your hybrid would look like

• List the traits it would get from each of its parents

• List the advantages and disadvantages it would have in the wild

OTHER HYBRIDSSplake- hybrid of male brook trout

and female lake troutAfricanized honey bee- African and

European bees, “killer bees”Beefalo-cattle and bisonZebroid-zebra and horse