Write everything that is underlined Section 6-1 Chromosomes & Meiosis Section 6-1 Chromosomes & Meiosis.

Write everything that isWrite everything that is underlinedunderlined

Section 6-1Section 6-1“Chromosomes “Chromosomes

& Meiosis& Meiosis””

6.1 Chromosomes and Meiosis

One of Biology’s Essential QuestionsOne of Biology’s Essential Questions::At the end of this unit you will need to be able to At the end of this unit you will need to be able to

answer this question …answer this question …

The Big Question: WHY ARE ALL The Big Question: WHY ARE ALL HUMANS DIFFERENT?????HUMANS DIFFERENT?????

……Look around the room- no one is Look around the room- no one is exactly like youexactly like you

……Your siblings are not exactly like you Your siblings are not exactly like you (unless you have an identical twin)(unless you have an identical twin)

……There is an amazing process that There is an amazing process that makes us all different … makes us all different … meiosismeiosis

6.1 Chromosomes and Meiosis

KEY CONCEPT: KEY CONCEPT: Gametes have half the number of Gametes have half the number of chromosomes that body cells havechromosomes that body cells have

6.1 Chromosomes and Meiosis

Fill out this chart for reference as we move along in our Fill out this chart for reference as we move along in our notes notes

TermTerm DefinitionDefinition

Somatic CellSomatic Cell

GameteGamete

Homologous Homologous ChromosomeChromosome

AutosomeAutosome

Sex ChromosomeSex Chromosome

Sexual ReproductionSexual Reproduction

FertilizationFertilization

DiploidDiploid

HaploidHaploid

MeisoisMeisois

6.1 Chromosomes and Meiosis

A. Body cells and gametesA. Body cells and gametes

1. Body cells are 1. Body cells are alsoalso called somatic cells called somatic cells

2. Gametes are sex cells: egg and sperm2. Gametes are sex cells: egg and sperm

–Gametes have DNA that can be passed to Gametes have DNA that can be passed to offspringoffspring

(Psst…Fill out your vocabulary chart…)(Psst…Fill out your vocabulary chart…)

body cellsbody cells sex cells (sperm)sex cells (sperm) sex cells (egg)sex cells (egg)

6.1 Chromosomes and Meiosis

Take a Vote!!!!Take a Vote!!!!

Is a skin cell a somatic cell or a gamete?Is a skin cell a somatic cell or a gamete?

-Somatic-Somatic

Is an egg a somatic cell or a gamete?Is an egg a somatic cell or a gamete?

-Gamete-Gamete

What is a liver cell considered- somatic or gamete?What is a liver cell considered- somatic or gamete?

-Somatic-Somatic

What is another type of somatic cell?What is another type of somatic cell?

-Sperm Cell-Sperm Cell

6.1 Chromosomes and Meiosis

1.1. Your body cells have 23 Your body cells have 23 pairs of chromosomespairs of chromosomes

2.2. The first 22 pairs of The first 22 pairs of chromosomes are chromosomes are autosomesautosomes

3.3. Sex chromosomes (X Sex chromosomes (X and Y) determine what and Y) determine what gender you will be (male gender you will be (male or female)or female)

B. Autosomes and sex chromosomesB. Autosomes and sex chromosomes

6.1 Chromosomes and Meiosis

4.4. Homologous pairs Homologous pairs of chromosomes of chromosomes have genes for the have genes for the same traitssame traits

5.5. For each For each homologous pair, homologous pair, one chromosome one chromosome comes from each comes from each parentparent

6.1 Chromosomes and Meiosis

Think-Pair-Share (2 min.)Think-Pair-Share (2 min.)

• Do you believe that homologous chromosomes are Do you believe that homologous chromosomes are identical to each other? identical to each other?

• Why or why not???Why or why not???

6.1 Chromosomes and Meiosis

1.1.Diploid (2Diploid (2nn) cells have two ) cells have two copies of every chromosomecopies of every chromosome

– Body cells are diploidBody cells are diploid

– Half the chromosomes come Half the chromosomes come from each parentfrom each parent

C. Diploid and Haploid

6.1 Chromosomes and Meiosis

2.2. Haploid (Haploid (nn) cells have one copy of ) cells have one copy of every chromosomeevery chromosome

–Gametes (sex cells) are haploidGametes (sex cells) are haploid

–Gametes have 22 autosomes and 1 Gametes have 22 autosomes and 1 sex chromosomesex chromosome

6.1 Chromosomes and Meiosis

Quick Thinking!Quick Thinking!

• You can write, draw, diagram, or write a quick song You can write, draw, diagram, or write a quick song for your answer…for your answer…

• Why is it Why is it soso important that gametes are important that gametes are haploid cells? What would happen if, haploid cells? What would happen if, for some reason, it occurred that one for some reason, it occurred that one wasn’t?wasn’t?

6.1 Chromosomes and Meiosis

D. Fertilization: When the egg and D. Fertilization: When the egg and sperm cell unite sperm cell unite

1.1. 2 haploid cells unite to form a cell 2 haploid cells unite to form a cell (zygote) that once again has the (zygote) that once again has the diploid number of chromosomesdiploid number of chromosomes– Chromosome number must be Chromosome number must be

maintained in animalsmaintained in animals– Many plants have more than two Many plants have more than two

copies of each chromosomecopies of each chromosome

2.2. A zygote grows to be a humanA zygote grows to be a human

6.1 Chromosomes and Meiosis

REMEMBER THISREMEMBER THIS

• Mitosis and meiosis are types of Mitosis and meiosis are types of nuclear division that make different nuclear division that make different types of cellstypes of cells

• Mitosis makes more identical Mitosis makes more identical diploid cellsdiploid cells

6.1 Chromosomes and Meiosis

• Meiosis makes haploid cells from diploid Meiosis makes haploid cells from diploid cells and:cells and:– occurs in sex cellsoccurs in sex cells

– produces gametesproduces gametes

6.1 Chromosomes and Meiosis

MeiosisMitosis

Compare and Contrast MITOSIS and MEIOSIS on a separate sheet of paper based on what you

already know about both. Turn in at the end of the period before you walk out the door.

Differences go HEREThings they have in common go HERE

Differences go HERE