Meiosis VocabularyMeiosis Vocabulary

Functions and Pictures…Functions and Pictures…

What is DNA?

• DeoxyriboNucleic Acid– the genetic

material that carries information about an organism and is passed from parent to offspring

What are Chromosomes?

• Rod-shaped cellular structures made of condensed chromatin; contain DNA that carries the genetic information which controls inherited characteristics such as eye color and blood type

• A chromosome pair looks like an X

• You have 23 PAIRS(2n-diploid) in every cell – (one from dad / one from

mom)

• Except for sperm or egg cells which have only 23 (no pairs)

What is Asexual Reproduction?

• The reproductive process that involves only one parent and produces offspring that are identical to the parent

What is Sexual Reproduction?

• The reproductive process that involves two parents who combine their genetic material to produce a new organism, which differs from both parent

What is Meiosis?

• Produces gametes- sex cells (sperm and egg) by which the number of chromosomes is reduced by half

What are Homologous chromosomes?

• Chromosomes from the female and male that contain the same genes (ex. #1 from male and #1 from female)

Random Chromosome Segregation

• Are all the four haploid cells that result from meiosis the exact same? Why or why not?

• What causes this randomness?

• Random segregation of homologous chromosomes and sister chromatid

• Crossing over

Independent Assortment

What are Gametes?

• A sperm cell or an egg cell, haploid = n

What is Fertilization?

• The joining of a sperm cell and an egg cell

First…the sperm has to get there!

What is a Zygote?

• A fertilized egg, produced by the joining of a sperm and an egg

• This is right after fertilization happening

Mitosis vs. Meiosis

What happens in Reproduction?DNA is passed from parent to offspring in two possible ways…

Sexual Reproduction• 2 parents• Produces a

combination of chromosomes that is different from the parent

• Creates genetic diversity

Asexual Reproduction• 1 parent• Offspring have same

chromosomes and is identical to the parent

What are the benefits?

Sexual Reproduction

• Creates Genetic Diversity– Children are different

from the parents– If one dies from a

disease, others MAY be able to survive it

Asexual Reproduction

• It is Fast…– Can produce lots of

offspring (kids) really fast! (20 minutes)

• Only need one “parent”

What are the drawbacks?

Sexual Reproduction

• You need two “parents”

• Can be slow– Elephants are

pregnant for 2 years!

Asexual Reproduction

• The offspring (kids) are the same as the “parents”– If one can die from a

disease, then all can die from the same disease…

– All may have illness

What happens inSexual Reproduction?

Produces gametes (sex cells)

•Female (eggs)•Large cells•Don’t move

•Male (sperm)•Smaller cells

•Flagella: used to move cell toward egg cell

Fertilization (joining of egg & sperm)

Zygote (fertilized egg)

Advantage: creates offspring with genetic diversity

New living organism with genetic variation

How many chromosomes does a human cell have?

•46 or 23 pairs

What happens in meiosis?

• Meiosis is the process when chromosome pairs separate to form four new sex cells with half the number of chromosomes

Parent cell (copies DNA)

Mitosis (cell divides)

Meiosis: cells divide again (sperm or egg cells)

46

92

46 46

23 23 2323

What happens when sex cells combine?

• When sex cells (gametes) combine to produce offspring, each sex cell will contribute to the offspring half (23) the normal number of chromosomes (46)

sperm egg23

23

46

Closure Questions1. Explain the difference between asexual and sexual

reproduction.2. What is the advantage of sexual reproduction?3. What are the two types of gametes made in sexual

reproduction?4. How many chromosomes do human cells have?5. At the end of meiosis how many cells are made?6. At the end of meiosis, the new cells have how many

chromosomes compared to the original parent cell?7. When sex cells combine to produce offspring, each sex

cell will contribute how many number of chromosomes?