6.1 Chromosomes and Meiosis REVIEW OF MITOSIS. Mitosis is _____________________________________ It...

6.1 Chromosomes and Meiosis

REVIEW OF MITOSIS.

• Mitosis is _____________________________________• It refers to the process of replication of ___________ cells.• Two purposes of mitosis: ____________ and __________• It results in __________________________________

(_______________________________________)

CELL DIVISION/REPRODUCTIONBODY

REPAIR GROWTH

TWO IDENTICAL DAUGHTER CELLS

2 CELLS WITH THE SAME DNA AS ORIGINAL CELL

Meiosis - Chapter 3


You have body cells and gametes.

• Body cells are also called _________________ cells.• Germ cells develop into ______________.

– Germ cells are located in the _________ and ________.– Gametes are sex cells: ______________________.– Gametes have _______ that can be passed to offspring.

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

somatic

gametesovaries testes

Egg and sperm

DNA


KEY CONCEPT Gametes have ______________________ of ______________________ that body cells have.

½ the numberchromosomes


AUTOSOMES

ONLY

1. Your cells have __________ different type of chromosomes:- ___________________ - Chromosomes that carry

_____________ body traits- ________________ - chromosomes that carry

genes specific to the ___________ of an organism

SEX/GENDER

SEX CHROMOSOMES

2

EXAMPLES OF AUTOSOMAL TRAITS

EXAMPLES OF SEX CHROMOSOME TRAITS


• Your body cells have _______ pairs of chromosomes.- Chromosome pairs

# 1-22 are ________________.

• Sex chromosomes, # ______determine gender in humans. They are referred to as _________________

Your cells have autosomes and sex chromosomes.

Homologous pairs

23

X and Y

23


Understanding Homologous Chromosomes

– ____________________of chromosomes have the same structure.

– For each homologous pair, one chromosome comes _____________________.from each parent

AUTOSOMES

From Mom

From Dad

Gene for hair texture

Allele for straight hair

Allele for curly hair


Understanding Sex Chromosomes

– ____________________do _________ always have the same structure.

– Each parent still contributes one sex cell, BUT depending upon the parent, they can give either an _____________________.X or a Y

Sex Chromosomes NOT


Body cells are diploid; gametes are haploid.

• Fertilization between egg and sperm occurs in sexual reproduction.

• Diploid (2n) cells have two copies of every chromosome.– n represents the “pairs of chromosomes”

Human = 2n = __46___________________________

Goldfish = 2 n = _96___________________________

Pea = 2n = __18______________________________

– Body cells are diploid.

– Half the chromosomes __haploid_______________________.


• Haploid (n) cells have ________________ of every chromosome.– Only contain DNA from ______________________

- Gametes have ___ autosomes and __ sex chromosome.

Sex cells, (______________) are haploid. GAMETESONLY ONE

ONLY ONE PARENT

22 1


• Chromosome number must be _____________ in animals.

• Many plants have more than two copies of each chromosome.• Mitosis and meiosis are types of nuclear division that make

_________________ types of cells.• Mitosis makes more _________________ cells. (____________)• Meiosis makes more __________________ cells.(____________)

MAINTAINED

2 DIFFERENTSOMATIC/BODY

GAMETES/SEX

DIPLOID

HAPLOID


• Meiosis makes _______________ cells from diploid cells.

– Meiosis occurs in _______________ cells. – Meiosis produces _______________. (_________________)

HAPLOID

SEX

GAMETES SPERM & EGG


PROPHASE 1

METAPHASE 1

ANAPHASE 1

TELOPHASE 1 / PROPHASE 2

METAPHASE 2

ANAPHASE 2

TELOPHASE 2

____________________________________

____________________________________

____________________________________

____________________________________

____________________________________

____________________________________

____________________________________


Sister Chromatids

Nuclear Membrane

Centrioles Fibers

Shorten and Thicken. “Double

File” Find their “match” or pair up,

(one from mom with one from dad)

Begins to break down

Move apart from one another

Form between centrioles


Sister Chromatids

Nuclear Membrane

Centrioles Fibers

Become attached to the fibers, pulled to middle of cell

Remains dissolved

move to opposite ends

of cell

Stretch between two

ends of the cell


Sister Chromatids

Nuclear Membrane

Centrioles Fibers

Pairs pulled apart by fibers.

Pairs are separated…

Sisters/copies are still connected

Remains dissolved

Still at cell’s poles

Pull matching pairs apart


Sister Chromatids

Nuclear Membrane

Cell Membrane Fibers

Each end of cell has HALF the

number of chromosomes. Chromosomes

DO NOT unwind.

DOES NOT reform

Begins to pinch in until the

cytoplasm is divided in half

forming two new cells

DO NOT disappear


Sister Chromatids

Nuclear Membrane

Centrioles Fibers

Still coiled Has not reformed

Move apart from one another

Re-form between centrioles


Sister Chromatids

Nuclear Membrane

Centrioles Fibers

Become attached to the fibers. Are

pulled to middle of cell

(Single File)

Remains dissolved

Move to opposite ends

of cells

stretched between ends of cell. Are

attached to center of sister chromatids


Chromatids Nuclear Membrane

Centrioles Fibers

Sisters are pulled apart by fibers.

Each chromatid is separate from

its “sister”

Remains dissolved

Still at cell’s poles

Pull each chromatid

toward opposite ends

of cell


Chromatids Nuclear Membrane

Cell Membrane Fibers

Each end of cell has HALF and

SINGLE chromosomes.

Begins to reform Begins to pinch in until the

cytoplasm is divided in half

forming two new SEX cells, (4

TOTAL)

Begin to disappear


KEY CONCEPT During meiosis, diploid cells undergo _______ cell divisions that result in _______________ cells.

2HAPLOID


Cells go through two rounds of division in meiosis.

• Meiosis reduces chromosome number and creates _______________________________. GENETIC DIVERSITY


• Meiosis differs from mitosis in significant ways.

– Meiosis has _____ cell divisions while mitosis has one.– In mitosis, _____________chromosomes never pair up.– Meiosis results in ____________ cells; mitosis results in

______________ cells.

2

HOMOLOGOUS

HAPLOID

DIPLOID


• Meiosis I and meiosis II each have four phases, similar to those in mitosis.

homologous chromosomes

sisterchromatids

sisterchromatids

– Pairs of homologous chromosomes separate in ___________.– Homologous chromosomes are ___________ but not identical.

– One from mom One from dad– Brown Eyes - Blue Eyes– Attached Earlobes -Free Earlobes– Type B blood -Type A blood

– Sister chromatids divide in _____________.

MEIOSIS 1

SIMILAR

MEIOSIS II


• Meiosis I occurs after DNA has been replicated.

• Meiosis I divides homologous chromosomes in four phases.


• Meiosis II divides sister chromatids in four phases.

• DNA is not replicated between meiosis I andmeiosis II.


MEIOSISANIMATION

MORE MEIOSIS

EXAMPLES


Sex cells develop during puberty.


•4 CELLS ARE PRODUCED

•EACH CELL HAS ONLY HALF THE NUMBER OF CHROMOSOMES AS THE ORIGINAL

•MALES: ALL FOUR CELLS ARE “GOOD” SPERM

•FEMALES: 3 CELLS ARE CONSIDERED “POLAR BODIES” ONLY 1 CELL IS A VIABLE EGG

(THIS IS DUE TO AN UNEVEN DIVISION OF CYTOPLASM DURING MEIOSIS)


Haploid cells develop into mature gametes. • _________________ is the

production of gametes.• Gametogenesis differs between

____________ and __________.

– Sperm become ____________ and _____________.

– Sperm primarily contribute ____ to an embryo.

– Eggs contribute _______, _____________, and ____________ to an embryo.

– During meiosis, the ______ gets most of the contents; the other cells form _________________.

Gametogenesis

MALES FEMALES

STREAMLINEDMOTILE

DNA

DNACYTOPLASMORGANELLES

DNA

POLAR BODIES


Make sure to include the cell membrane,

nuclear membrane, chromosome,centrioles, and fibers.

13.1 Ecologists Study Relationships

1.__________________________________2.__________________________________3.__________________________________4.__________________________________5.__________________________________Process: __________________________________________________________

1.__________________________________2.__________________________________3.__________________________________4.__________________________________5.__________________________________6.______________________7.____________________________________

1

12

3

4

5

1

2

3

4

5

6

7


The sperm is the smallest cell in the body, whilst the egg is the largest,it is estimated that it will take 175,000 sperm to weigh as much as a female egg, which is a lot of sperm!

Females are born with all the oocytes (eggs) that they will ever have in a lifetime?

Infertility: sperm counts drop as low as 20 million per ml

Average males produce 150 million sperm daily!

6.1 Chromosomes and Meiosis REVIEW OF MITOSIS. Mitosis is _____________________________________ It...

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