1. Life Cycle
Unit 6 Lesson 1

2. Explain the difference in mitosis and meiosis.
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CLASS OBJECTIVES
Describe how cells, tissues, and organs work together in the human body.
Explain the difference in mitosis and meiosis.
Identify ways that environment, heredity, and lifestyles affect human development.
REMINDERS

3. Life Cycle You began your life as a single microscopic cell.
That cell divided over and over again until it formed the trillions of cells that now make up your body.

4. Cells Cells are the basic units, or building blocks of life.
There are many different kinds of cells in the human body.
Each kind of cell does a specific job.

5. Tissues Cells that do similar jobs make up tissues.
There are several different types of tissues.
Each tissue has a different function and look.

6. Organs
Different kinds of tissues are combined in larger structures called organs.
Organs are body parts that perform particular functions.

7. Systems Group of organs that work together form systems.
Grouping organs into systems makes it easier to understand their functions.

8. What Makes You Unique Every individual is unique.
Each of us has our own looks, abilities, and personality.

9. What Makes You Unique
There are several different factors as to how we develop.
These factors can be grouped into three different categories:
Heredity
Environment
Lifestyles

10. Heredity
Heredity is the passing of traits from parents to their children.
Has anyone ever told you that you look or act like someone else in your family?

11. Heredity In each cell of the human body there is a nucleolus.
Inside the nucleolus are 46 chromosomes.
Chromosomes are threadlike structures that carry the codes of inherited traits.

12. Heredity
When a cell divides to make a new cell, the 46 chromosomes are copied so that the new cell has the same chromosomes as the original.
On each of the chromosomes are different genes.
Genes are basic units of heredity.

13. Heredity
Genes carry codes for specific traits, such as hair color and eye color.
It is the different genes that make you unique.

14. Assignment 1 List three traits that you think you get from your mom.
List three traits that you think you get from your dad.

15. How It Works
You receive 23 chromosomes in the egg cell from your mother.
You receive 23 chromosomes in the sperm cell from your father.

16. How It Works
When the egg and the sperm cell join (fertilization) they combine together to make 46 chromosomes.

17. How it Works
This pictures shows several sperm cells (each carry different combinations of genes from dad) trying to fertilize one egg cell (which has genes from mom).
Depending on which sperm cell actually fertilizes the egg will determine the genetic traits and sex of the baby.

18. How it Works
Your gender is determined by the 23 set of chromosomes.

19. How It works
If you are a boy, you will have an X and Y chromosomes on the 23 pair

20. How It Works
If you are a girl, you will have an X and X chromosomes

21. Normal Cell Division Normal cell division is called mitosis
46 Chromosomes
Normal cell division is called mitosis
When normal cells divide, the chromosomes double
The cell splits and each cells ends up with the same 46 chromosome.
92 Chromosomes
46 Chromosomes
46 Chromosomes

22. Sex Cell Division Sex cell division is called meiosis
46 Chromosomes
Sex cell division is called meiosis
When sperm and egg cells divide, the chromosome double.
Then they split into two cells with 46 chromosomes
Then they split a second time into two cells only leaving 23 chromosomes in the cell.
92 Chromosomes
46 Chromosomes
46 Chromosomes
23 Chromosomes
23 Chromosomes

23. Sperm Sex Cell Division
46 Chromosomes
X and Y chromosome
With sperm cells, the sex divides a second time leaving only 23 chromosomes in the new cells.
This means that some cells will only have an X chromosome and some will only have a Y chromosome.
92 chromosome
X and y chromosome
X and Y – 46 Chromosome
X and Y – 46 Chromosome
X Y
X Y
23 chromosomes each

24. Sex Cell Division
X and X Chromosome
In the egg cells, when the cell divides one set of the 23 cells in non functional.
When the cell divides again, it creates one cell that carries 23 chromosomes and another non functional cell.
This means the egg cell will always have only an X chromosome.
X Chromosome
Non functioning Cells
X Chromosome

25. Assignment #2 (write on the back side)
With your partner answer the following question.
Knowing that eggs cells only carry the X chromosome explain how the sperm cells are the ones that determine the gender of a baby.

26. Genetic Disorders
Sometimes genes from one or both parents can have flaws.
When genes are flawed, a baby may be born with a genetic disorder.
A genetic disorder is caused partly or completely by a defect in genes.

27. Assignment #3
With your partner come up with three genetic disorders you learned about in the last unit on Non-Infectious Diseases.

28. Common Genetic Disorders
Sickle cell disease
Cystic Fibrosis
PKU
Muscular Dystrophy
Hemophilia
Down Syndrome

29. Environment
Besides heredity, the second factor to influence the health of a fetus and newborn child is environment.
Environment is the sum total of a person’s surroundings.

30. Environment
In the last unit you learned that carcinogens are things that can cause the change in DNA of a cell.
Examples of common carcinogens:
Pollution
Smoke
UV rays
Radiation
Drugs
Chemicals

31. Lifestyle Choices
Sometimes choices in our lifestyle and things in our environment can cause harm to a developing fetus.
Birth defects are abnormalities present at birth that cause physical or mental disability or death.

32. Lifestyle and Environmental Factors
Poor Nutrition
All the nourishment a fetus gets is from its mother.
Pregnant women who do not follow healthy eating guidelines may experience one or more the following consequences:
Babies born too early
Low birth weight
Mental and physical problems

33. Lifestyle and Environmental Factors
Alcohol
Alcohol changes the normal cell development in the unborn fetus and cause FAS (Fetal Alcohol Syndrome).
FAS is a pattern of physical and mental problems in children whose mothers drank alcohol during pregnancy.
Even the smallest amount of alcohol consumption, and any stage of pregnancy, can cause FAS.
It is important to avoid alcohol completely when pregnant.

34. Lifestyle and Environmental Factors
Medication and Drugs
A pregnant women should avoid all medications and drugs, unless approved by her physician.
This includes over-the-counter drugs like cough syrup and headache medication.
Medications and drugs can change the proper development of the fetus, causing birth defects.

35. Lifestyle and Environmental Factors
Tobacco
A fetus who is exposed to tobacco can be born prematurely and with a low birth weight.
Pregnant women should not smoke themselves, and avoid breathing second hand smoke.

36. Lifestyle and Environmental Factors
There are many infections that can cause serious health problems to a developing fetus.
These infections include Rubella and German Measles as well as STI’s (sexually transmitted infections).
These infections can cause:
Deafness
Blindness
Brain Damage
Physical Abnormalities
Zika Virus

37. Quick Check
A _____ _____is abnormalities present at birth that cause physical or mental disabilities.
A _____ _____is caused partly or completely by a defect in genes.
List four steps a pregnant women can take to protect her own health and the health of her developing fetus
____ is the passing on of traits from parents to offspring.
You get ___ chromosomes from both your mom and dad, giving you a total of ___.

38. Quick Check
A Birth Defects is abnormalities present at birth that cause physical or mental disabilities.
A Genetic Disorder is caused partly or completely by a defect in genes.
List four steps a pregnant women can take to protect her own health and the health of her developing fetus
Heredity is the passing on of traits from parents to offspring.
You get 23 chromosomes from both your mom and dad giving you a total of 46.