Cell Division Day 4: Gametogenesis

Types of Meiosis

Match

Match the following

Prophase II

Metaphase II

Anaphase II

Telophase II

• Prophase II

• Metaphase II

• Anaphase II

• Telophase II

Multiple Choice

Which cell is undergoing meiosis?

• cell 3
• cell 4
• cell 1
• cell 2

Drag and Drop

Meiosis I separates

Placeholder

Meiosis II separates​

Placeholder

Drag these tiles and drop them in the correct blank above

Homologous Chromosomes

Sister Chromatids

Multiple Choice

In which stage of MEIOSIS does crossing over occur? (The exchange of DNA between homologous chromosomes)

• Anaphase I

• Metaphase I

• Prophase I

• Telophase I

Labelling

Label the stages shown

Drag labels to their correct position on the image

Metaphase II

Metaphase I

Multiple Choice

What phase of Meiosis is in this picture?

• Prophase I

• Metaphase I

• Anaphase I

• Telophase I

Multiple Choice

In Metaphase II, _________ line up on equatorial plane.

• homologous pairs of chromosomes

• single chromosomes (made up of 2 sister chromatids)

• tetrads

• centrosomes

Match

Match the following:

• sperm

• egg

• zygote

• gamete

• meiosis

male gamete

female gamete

diploid

haploid

formation of gametes

• male gamete

• female gamete

• diploid

• haploid

• formation of gametes

Multiple Choice

In this diagram homologous chromosomes are moving to opposite poles of the cell. What phase is  shown in the diagram?

• anaphase 1

• anaphase 2

• metaphase 1

• telophase 1

Multiple Choice

What phase is shown here?

• Anaphase I
• Prophase I
• Metaphase II
•  Metaphase I

Multiple Choice

What stage of meiosis is this?

• Prophase 1

• prophase 2

• Metaphase 1

• Metaphase 2

Multiple Choice

What stage of meiosis is depicted?

• prophase 1

• anaphase 1

• anaphase 2

• telophase 2

Multiple Choice

What phase of meiosis is this?

• prophase 1

• Metaphase 2

• telophase 2

• anaphase 1

Multiple Choice

During meiosis what stage will occur next?

• telophase
• anaphase I
• metaphase I
• prophase

Match

Match the following

• Prophase I

• Metaphase I

• Anaphase I

• Anaphase II

• Telophase II/Cytokinesis

Homologous pairs exchange DNA (crossing over)

Homologous pairs line up in the middle

Homologous pairs are separated

Sister chromatids are separated

Four nuclear membranes form; there are now haploid cells.

• Homologous pairs exchange DNA (crossing over)

• Homologous pairs line up in the middle

• Homologous pairs are separated

• Sister chromatids are separated

• Four nuclear membranes form; there are now haploid cells.

Multiple Choice

During Prophase II, what major event occurs?

• Chromosomes duplicate.

• The nuclear envelope breaks down, and chromosomes condense.

• Homologous chromosomes pair up.

• Chromosomes line up at the equatorial plate as pairs.

Match

Match the following description to the correct stage of meiosis I. Answers may be used only once or not at all.

• Chromosome number is reduced from 2n to 1n.

• Two sister chromatids reach opposite poles of the cell.

• Homologous chromosomes become visible, condense, and form pairs. Crossing over can occur.

• Homologous pairs of chromosomes line up on the equator.

• DNA is replicated and proteins are synthesized.

anaphase I

telophase I

prophase I

metaphase I

interphase

• anaphase I

• telophase I

• prophase I

• metaphase I

• interphase

Multiple Choice

What distinguishes Meiosis II from Meiosis I?

• Meiosis II involves the duplication of DNA.

• Meiosis II results in the separation of sister chromatids.

• Meiosis II separates homologous chromosomes.

• Meiosis II occurs without prior DNA replication.

Are all organisms only male or female?

As we talked about with plants, there are some organisms that are exclusively male, exclusively female, or both! When organisms have both male and female gonads (reproductive organs), we call them hermaphrodites.

Some common examples of hermaphroditic animals are earthworms, clownfish, and snails.

Although one organism can contain both types of gonads, self-fertilization is exceptionally rare and typically only done when there is an unusually/dangerously low population density or the organism has limited mobility.

How are sperm and eggs made?

We call the large, sessile (doesn’t move) female gamete an Egg
We call the smaller, motile (moves) male gamete a Sperm

Genesis=Formation/Make

The formation of specialized sex cells or gametes=Gametogenesis

The formation of male sex cells or sperm=Spermatogenesis

The formation of female sex cells or eggs=Oogenesis

Multiple Choice

What is gametogenesis?

• The formation of specialized sex cells or gametes

• The formation of a large, sessile female gamete called an egg

• The formation of a smaller, motile male gamete called a sperm

• The process of fertilization between egg and sperm

How are sperm made?

• The production of sperm occurs in the male gonad- the testes.

• Sperm develop from unspecialized cells called spermatogonia.

• Spermatogonia develop over time to form something called primary spermatocytes.

• During the first meiotic division the primary spermatocytes produce two secondary spermatocytes.

• During the second meiotic division the two secondary spermatocytes produce four spermatids.

• The spermatids develop into mature sperm
  
  Some animals only produce sperm during specific mating seasons. In others, sperm are produced all year long

Labelling

Label the spermatogenesis diagram

Drag labels to their correct position on the image

Primary spermatocytes

Secondary spermatocytes

spermatogonia

spermatids

Drag and Drop

A is the​

Placeholder

which contains the nucleus. B is the ​

Placeholder

filled with E, which are ​

Placeholder

. C is the​

Placeholder

. D, which encompasses A, is called the​

Placeholder

and is filled with enzymes to help burrow into the Egg Cell.

Drag these tiles and drop them in the correct blank above

Head

Neck

Flagella

Acrosome

Mitochondria

How are eggs made?

• The production of eggs (Ova) occurs in the female gonad- the ovaries.

• Mature eggs develop from oogonia which enlarge to form the primary Oocyte

• The primary oocyte undergoes the first meiotic division, producing one secondary oocyte and one smaller polar body

• The secondary oocyte undergoes the second meiotic division producing one ootid and one polar body.

• All polar bodies disintegrate/dissolve

• The ootid grows into a mature ovum/egg cell

• The ovum is a nonmotile (doesn't move) cell that contains a small quantity of stored food in the yolk.

• The ovum is larger because of the unequal dividing of the cytoplasm

Multiple Choice

At the end of meiosis, how many complete/operational sex cells are created for each original cell?

• 2 for males; 2 for females

• 1 for males; 4 for females

• 4 for males; one for females

• 1 for males; 1 for females

Multiple Choice

The diagram represents several steps in the reproduction and growth of houseflies. Each circle in the diagram represents a cell. Which labeled step represents the formation of a zygote?

• Step 1

• Step 2

• Step 3

• Step 4

How do Sperm Meet Eggs?

Fertilization is the union of an egg cell nucleus and a sperm cell nucleus.
It occurs when a Sperm Cell penetrates the cell membrane of an Egg Cell and the haploid nucleus of the sperm unites with the haploid nucleus of the ovum, forming a diploid Zygote nucleus.

This can happen in one of several ways:

• Internally

• Externally

• Parthenogenesis

Internal Fertilization

Eggs are fertilized within the female body. Specialized organs are needed to deliver sperm from the male body into the female body. Fewer eggs are formed, but many sperm are formed.

All mammals utilize this strategy, including marine mammals. It is commonly found among animals reproducing on land. However, some aquatic organisms also use this strategy, such as shark and lobster.

External Fertilization

AKA: Broadcast Spawning

Each parent releases hundreds to thousands of gametes simultaneously, directly in the water. The sperm will use the water to swim to the egg. Eggs are fertilized outside of the female body.

This takes place only in animals that breed in water Ex: Salmon, Coral, Frogs, Urchin, etc.

This strategy has a few risks.

1. Sperm and Egg never Meet

2. Eggs Eaten

3. Changes in temperature/pH cause death

Multiple Choice

Which best explains why internal fertilization is a greater advantage to an  organism than external fertilization?

• Internal fertilization prevents mutations from occurring.

• Internal fertilization provides a protective environment for fertilization to   occur.

• Internal fertilization produces a large number of zygotes. 

• Internal fertilization decreases the chance of mitotic cell division.

Parthenogenesis: The Ultimate Self-Love

Development of an unfertilized egg into and an adult animal

It's a type of sexual reproduction
Usually occurs insects (invertebrates) such as bees, wasps, aphids, and ants. In bees, the queen bee mates once. She then produces either unfertilized or fertilized eggs. The unfertilized eggs become male drones while fertilized eggs become female workers or queens

But, can occur in SOME vertebrates; sharks, some lizards, a single species of vole, and snakes. All offspring will be female in this case. No males can be produced.

Advantages- can reproduce even if there are no males.

Disadvantages- less diversity which means resulting pups may be less able to fight off infections or deal with life’s challenges

Multiple Choice

What phase is shown here?

• Anaphase I
• Prophase I
• Metaphase II
•  Metaphase I

Multiple Choice

What phase is this?

• Interphase II
• Prophase I
• Metaphase I
• Anaphase II

Multiple Choice

Which diagram demonstrates how crossing-over contributes to genetic variety during meiosis?

• A

• B

• C

• D

Drag and Drop

A pair of homologous chromosomes (a tetrad) is composed of ​ ​

Placeholder

matching chromosomes, and ​

Placeholder

sister chromatids.

Drag these tiles and drop them in the correct blank above

two

four

one

three

Multiple Choice

During meiosis, if an organism has 10 chromosomes, how many will the new daughter cells have?

• 10

• 8

• 5

• 2

Multiple Choice

During mitosis, if an organism has 10 chromosomes, how many will the new daughter cells have?

• 10

• 8

• 5

• 2

Drag and Drop

In mitosis the ​

Placeholder

daughter cells that are created are ​

Placeholder

. In meiosis the ​

Placeholder

daughter cells that are created are ​

Placeholder

Drag these tiles and drop them in the correct blank above

two

diploid

four

haploid

Multiple Choice

What do the cells look like at the end of mitosis?

• different from original cell

• identical to the original cell

• similar to the original cell

• none of these

Multiple Choice

During meiosis, homologous chromosomes exchange genetic material. This exchange of genetic material -

• increases the genetic variation

• reduces the diploid number to the haploid number

• increases the haploid number to the diploid number

• reduces the probability of mutations