DNA and Cell Replication
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Transcript of DNA and Cell Replication
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