By Mr. Simonds EQ: How are traits passed from parents to offspring? Meiosis & Karyotypes By Mr. Simonds EQ: How are traits passed from parents to offspring?

Vocabulary Meiosis – A type of cell division that produces sex cells with half the normal number of chromosomes.

Meiosis I

Meiosis II Prophase II Metaphase II Anaphase II Telophase II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Prophase II Metaphase II Anaphase II Telophase II The chromosomes line up in a similar way to the metaphase stage of mitosis. The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid (N) daughter cells.

Gametes – Sex cells (sperm and eggs) Haploid – The name for a cell that has half of its normal number of chromosomes. Ex. Gametes

Somatic Cells – Every non-sex cell (skin, nerves, muscle, etc) Diploid Diploid – The name for a cell that has two of every type of chromosome.

In each of our sex cells we have 23 chromosomes, one of each type. Humans have 23 pairs of chromosomes. That makes a total of 46 chromosomes. So our diploid number is 46. In each of our sex cells we have 23 chromosomes, one of each type. So our haploid number is 23.

Healthy Human Male

If the diploid number of an organism is 10, what is the haploid number? 5 If the haploid number of an organism is 15, what is the diploid number?

Homologous Chromosomes – A pair of the same type of chromosomes Homologous Chromosomes – A pair of the same type of chromosomes. You get one from your mom and one from your dad.

Review How many chromosomes would one of your skin cells have? 46 What is the haploid number for humans? 23

Review What are gametes? How many chromosomes do human gametes have? Sex cells (sperm and eggs) How many chromosomes do human gametes have? 23 If an organisms haploid number is 20 what is its diploid number? 40

Karyotyping By Mr. Simonds

What is a Karyotype Karyotype - a picture of a person’s chromosomes matched by pairs and arranged in order. To make a karyotype you need a picture of a persons DNA in chromosome form Then you match up chromosomes in pairs (23 pairs, including sex chromosomes)

Reasons for Karyotyping To check for genetic (chromosomal) disorders such as: Down syndrome Klinefelter syndrome Turner syndrome

What are the pairs? Autosomes – Chromosomes 1-22, they control most of the traits that make you.

What are the pairs? Sex Chromosomes – The 23rd pair of chromosomes (X & Y), they determine your sex (male or female).

Chromosomes & Gender A female has two X chromosomes. A male has one X and one Y chromosome. As long as there is a Y chromosome the fetus will become a male.

Karyotype of a Healthy Female

Karyotype of a Healthy Male

What is Down Syndrome? Down Syndrome – A disorder caused by an extra 21st chromosome. It causes delays in physical and intellectual development Also called Trisomy 21 Occurs in 1 out of every 800 live births Down syndrome is not related to race, nationality, religion or socioeconomic status. The most important fact to know about individuals with Down syndrome is that they are more like others than they are different.

Down Syndrome

Turner Syndrome Turner Syndrome – caused by having only one X chromosome. People with Turners become female. Occurs in 1 in 2000 to 1 in 2500 live births. Symptoms include short stature and lack of ovarian development. (They are sterile.)

Klinefelter Syndrome Klinefelter Syndrome – Caused by having two X and one Y chromosome. People with this become male. Occurs in 1 in 500 to 1 in 1000 live births. They are often tall and usually do not develop secondary sex characteristics such as facial hair, or underarm and pubic hair.

How do these disorders occur? Metaphase II Prophase II *Note that two of the chromosomes did not separate during anaphase Anaphase II

How do these disorders occur? Non-disjunction – When chromosomes fail to separate during meiosis. This causes most chromosomal disorders. *Note that two of the chromosomes did not separate during anaphase Anaphase II

How non-disjunction occurs. Gamete A Gamete B Telephase An individual resulting from Gamete A may have Down syndrome, trisomy 21, or Klinefelter syndrome. An individual resulting from Gamete B may have Turner syndrome. * Note that Gamete A has one extra chromosome and Gamete B has one less chromosome

Mitosis & Karyotypes (+ a little DNA) Review Mitosis & Karyotypes (+ a little DNA)

Meiosis Does the father or the mother cause the sex of the baby? Why? The mother can only donate an X chromosome

Healthy Human Female

Metaphase

Down Syndrome

Prophase Nucleus membrane breaking down Chromosomes formed

Healthy Human Male

Meiosis What cells undergo Meiosis? Sex Cells How much DNA or Chromosomes do you have after Meiosis? Half as much What cells undergo Mitosis? Body cells (Everything except for Sex cells)

Meiosis What does Haploid mean? Half the number of Chromosomes An organisms Diploid number is 12. What is its haploid number? 6 You have two of each type of chromosomes. Where do you get them from? One from your mom & one from your dad

Chromosomes separating Anaphase Chromosomes separating

What happened? Non-Disjunction Metaphase II Anaphase II

Telephase/ Cytokinesis

Which ones pair together?

DNA What do you make during Transcription? mRNA What process makes protein from mRNA? Translation