Life Cycle Unit 6 Lesson 1

Explain the difference in mitosis and meiosis. GET STARTED 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

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.

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.

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

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

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

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

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

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?

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.

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.

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

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

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.

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

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.

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

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

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

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

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

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

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

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.

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.

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

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

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.

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

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.

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

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.

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.

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.

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

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 ___.

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.