Inside a Cell

A Tour of the Chromosomes

Humans, giraffes, chickens, gorillas or watermelons are made of

cells

Inside every cell is

a nucleus

Inside every nucleus there are

chromosomes

In humans there are

46 chromosomes in all BODY cells 23 chromosomes in all SEX cells

(23 pairs) (23 single chromosomes)

Testes contain sperm cells (23 chromosomes)

Ovaries contain egg cells (23 chromosomes)

In cats there are 38 chromosomesin all body cells 19 chromosomes in all sex cells

...and in the sex cells??????

Why would sex cells have half the number of chromosomes as body cells?

I only have 19

chromosomes in my

sperm cells to give, my

love!

This is perfect! I have 19 chromosomes in my egg cells as

well. Together we can make a new kitten 1 cell big ....

with 38 chromosomes!!

Summarize What you have learned so far…

Summary of Chromosomes

• A cat has 38 chromosomes in all body cells but 19 (half the amount) in its sex cells. Sex cells are called sperm cells in males and egg cells in females.

*Some organisms have male and female parts on the same organism

• The number of chromosomes varies depending on the organism

*chromosomes contain tightly wound DNA. When you uncoil it you can see the double helix.

Complete Worksheet

Sex Cells Body Cells

Each chromosome is made of

DNA

DNA

• is Deoxyribonucleic acid• In one chromosome there is about 2 meters of

DNA (in a human body there are 3 trillion cells so there is 10-20 billion miles of DNA)

• That’s from here to Pluto 20 times + back 20 times

Scientists Who Discovered DNAhttp://www.youtube.com/watch?v=VegLVn_1oCE&safe=active

• Watson was a _________________. Crick was a __________________. They worked at Cambridge University in England.

• What did Rosalyn Franklin contribute to the discovery of DNA?

• What is the structure of DNA?

Structure of DNA

• Describe the structure of DNA.

Structure of DNA

• Describe the structure of DNA.• Double helix (twisted ladder)• Small sections of your DNA are your genes which

determine your traits.• Phosphate and sugar “backbone”• 4 nitrogen bases – Adenine (A)– Thymine (T) A & T always pair together– Cytosine (C)– Guanine (G) C & G always pair together

DNA

• holds the genetic codes that determine your traits (hair color, eye color, height, probability for certain diseases)

• can be mutated• holds information for directing all cell

activities!!

DNA has to be copied to all new cells. How does this happen?

• DNA (and all other cell parts) are “photocopied by MITOSIS!!!!!!!!!

Watch this mitosis video!http://www.youtube.com/watch?v=-G-3BDlnK58

Mitosis helps you*grow new cells*replace injured/damaged cells

Answers to “The Cell Cycle”• Reproduce cells• Interphase, chromatin, chromosome• Mitosis– Prophase, disappear, spindle fibers, double stranded

chromosome (called centromere)– Metaphase, line (middle)– Anaphase, contract, apart, opposite sides– Telophase, DNA, spindle fibers, nuclear membrane, chromatinCytoplasmic Division-sets of DNA, cell membrane, cell plateDaughter cells, begins again

To accomplish today….(period 2)• Homework– Survey at least 20 people for 4 traits. Record

results.– Create a bar graph (see p. 588)– Answer 3 questions on “Reading Human

Blueprint”• In-class– Onion cell mitosis (hand in as you finish)

• Mitosis Project due: Friday Sept 27

9-4 Projects for Friday, Tuesday Oct 1, Wednesday Oct 3

• Victor-story• Cyril Garry Alex – ppt• Kenny Milan Peter-ppt• Ella, Rachel – animation part 1, news report IPAD• Harleen,Prasansa-music video- SMARTBOARD

PROJECTS FOR TUESDAY, OCT 1• Falicity, Emily, Josh – candy poster CANDY• Muge, Kirndip, Somin-3D model• Owen, Vincent, Daniel, Devon

– animation - song (live) WEDS

Shirliz, Bacy, Noelle, Melina – video WEDS

Friday Sept 27, 2013 9-4

• Review “Onion Cell Mitosis”

• Hand in bar graphs (with chart) AND 3 questions ON SEPARATE PAPER!!

• Homologous Chromosomes

• Homework: Patterns in Human Traits

• Overdue work

• Tuesday is Lab B (Day 3)• TEST-Fri Oct 4

-Weds Oct 9

Friday Sept 27, 2013 9-9

• Hand in bar graphs (with chart) AND 3 questions ON SEPARATE PAPER!!

Today• Homologous Chromosomes• Homework: Patterns in

Human Traits• Overdue work

• Quiz Wednesday (day 3, 3 periods) *Mitosis (higher level)

*DNA Structure *Patterns in Human

Traits

• TEST-Mon Oct 7

Project Schedule for Next Week 9-9

• Tuesday Oct 1 • Wednesday Oct 2 (triple)

Answers for “Onion Cell Mitosis”1. metaphase______2. prophase________3. telophase_______4. interphase______5. interphase_______6. interphase_______7. anaphase________8. interphase______9. anaphase______10. interphase______11. metaphase_______12. telophase_______13. interphase____14. prophase_____15. interphase_____16. interphase______17. metaphase_____18. interphase_____

Math Problems19. What percentage of the cells are in interphase? 8 out of 18

8/18 x 100 = 44%

20. What percentage of the cells are in metaphase?3 out of 18

3/18 x 100 = 17%

21. A cell spends much more time in interphase than in mitosis.

22. The cell cycle is the continuous cycle of interphase, mitosis and CYTOPLASMIC DIVISION

23. tissue, stomach lining or muscle, organ, lungs or stomach, organ system, digestive system or nervous system.

Genetics

• Study of genes• Genes for a certain trait are found on

homologous chromosomes• (see handout)

Review: Inside every human body cell’s nucleus….there are

46

chromosomes

Think of the 46 chromosomes instead as 23 pairs of homologous chromosomes

For example, chromosomes labelled “1” carry GENES for the same TRAIT

What does it mean to be dominant?

• powerful

Genes Determine Your Traits

• Raise your hand if you have blue eyes• Keep it raised if you have one brown-eyed parent

and one blue-eyed parent• How was your eye color determined?• It was determined by the genes found on your

homologous chromosomes.• We call the list of the 2 genes that an organism has

for a particular characteristic their GENOTYPE• Geneticists study genotypes

Genotype

• 2 letter symbol• Capital letter for the dominant gene and the

same letter in lowercase for the recessive gene• Examples: BB, Bb, bb• Example: Genotype for brown eyes BB or Bb• Example: Genotype for blue eyes bb• Example Genotype for free earlobes Ff or FF

F dominant f (not dominant) recessive

Dominant & Recessive Genes

• When a single characteristic has only 2 traits (“either-or”) traits, we call the traits opposite traits

• Refer to the chart in your booklet• A dominant gene is one that functions even when

paired with a gene for the opposite trait.• A recessive gene is one that does not function

when paired with a gene for the opposite trait. It can only function (show) when it is paired with another recessive gene like itself.

Homozygous and Heterozygous

• A person can be homozygous for brown eyes or heterozygous for brown eyes

Writing Genotypes• Refer to your chart• Remember that the dominant gene is written

in capital letters• The recessive gene is written in lowercase

letters• Write the following genotypes:a) heterozygous brown eyesb) homozygous blue eyes

GREGOR MENDEL (1822-1884)- the “father of genetics”

Mendel’s Observations & Conclusions

Observations• (A) Tall x tall

• (D) Short x short

• (C) Tall x short

• (B) Tall x tall

Conclusions

Mendel’s Observations & Conclusions

Observations• (A) Tall x talloffspring tall

• (D) Short x short offspring short

• (C) Tall x short offspring tall

• (B) Tall x tall offspring ¾ tall, ¼ short

Conclusions• All tall pea plants had PURE

traits (homozygous tall)• All short pea plants had

PURE traits (homozygous short)

• Short is recessive and so tall is dominant (short trait DISAPPEARS)

• 75% dominant tall and 25% short

• Tall x tall

• Short x short

• Tall x short

• Tall x tall

Mendel’s Contributions:

• Alleles- the different forms a gene has for a trait Examples: If the trait is eye color the alleles are: blue, green, brown

Definitions for...

• Variation:

• Dominant:

• Recessive:

• Pure (homozygous)• heterozygous

Definitions for...

• Pure (homozygous):

• Heterozygous:

Definitions for...

• Variation:

• Dominant:

• Recessive:

• Pure (homozygous)• heterozygous

Complete “Writing Genotypes”Complete Review

• Josh, Emily – if you are sitting together you need to move!!!

• Can a non-tongue roller be HOMOZYGOUS for that trait? (Note: tongue rolling is dominant)

David Beckham

Milos Raonic

Venus Williams