U5 B2 2HVTTO

• Biologie
• Middelbare school
• havo, vwo
• Leerjaar 2

B2 Chromosomes

• Take off your jacket
• Put your things on your desk

       Book, notebook, pencil case

• Bag on the floor
  
• Read pages 106-108

Lessongoals

• Understand: I can explain that each parent contributes 50% of their chromosomes to the offspring by describing the role of egg and sperm cells.
• Understand: I can explain how the sex of a human is determined by the combination of X and Y chromosomes.
• Understand: I can explain how sexual reproduction leads to genetic variation by describing how different combinations of chromosomes occur during fertilisation.
• Apply: I can give examples of how offspring can look different from their parents due to the mixing of genetic material during reproduction.

Wheel of homework

Go to Lessonup.app and use this code

Reward

Penalty

Rewards

• +1 cm2 cheatsheet = you get to make a cheatsheet for a test. This starts being 1 by 1 cm. Everytime you earn this it gets 1 cm bigger to a max of 4 by 4 cm.
• 1/3 +0.5 = If you earn this 3 times you get to add 0,5 to one of your biology marks.
• Snitch = You can pick a classmate who also is checked for homework, you earn two V's (having 3 earns you a 1/3 +0,5)
• Too bad = You only get one V
  

penalties

• 45 min extra worktime = you need to come after school and do homework, this will last for 45 min or until the task is done
• Coloringpage = You get to pick a coloringpage, You need to color it and perform tasks that might be on it. You need to hand it in during the next lesson, If you don't you get 2 marks.
• 2/1 marks = a mark is an X, if you get 3 of these you will automaticly earn the 45 min extra worktime.
• Snitch = You can pick a classmate who also is checked for homework
• Lucky! = You don't get a penalty

Drawing

Draw a cell with DNA inside it

Use what you know about DNA and cells to complete this task.

Follow the tips below to help you do your best.

Tips:

• Start by drawing a large cell. Inside the cell, draw the organelle where the DNA is stored. (Do you remember the name of this organelle?)
• Is the DNA floating freely in the cell, or does it have a specific shape? What is that shape?
• Use colours to show which DNA comes from which parent.
• How much DNA do you need to draw to show a body cell? (It doesn’t have to be a human cell.)

DNA in the cells of the intestines, also contains genes for hair color

1. True
2. False

Chromosomes are contained in specialized parts of your cells.
What is the name of this part? (1 word)

During summer, Jack likes to do lots of sunbathing. Because of this, he gets a tan.

What has happened?

1. His genotype has changed
2. His phenotype has changed
3. His genotype and phenotype have changed
4. His genotype and phenotype stay the same

How many chromosomes can you find in the nucleus of an eye cell? (number)

Do all cells in the body of a grown up healthy human contain 46 chromosomes?

1. Yes, all cells
2. No, but nearly all of them do
3. No, about half of them
4. No, only some cells

What is a gene?

Chromosomes form pairs.

1 pair contains information for the same hereditary characteristics.

1 pair contains the same genes 

(2 'versions', 1 on  each chromosome)

Having the same genes doesn’t mean everything is exactly the same!

A gene can be something like: eye colour, hair colour, or height.

The information in a gene can be different on each chromosome.

For the gene eye colour, for example, the information could be: blue, brown, or green.

!

Every (healthy) human has 2 versions of each gene.
Why do we have 2 versions of each gene?

A pair of chromosomes

These genes contain different information

Genes

Every coloured ring is 1 gene on the chromosome.

Some genes are bigger than others, they might contain more information.

Genes contain information about (part of) 1 characteristic.

The same characteristic can also have different variants.

example: Blue or green eye colour

When genes are shown with same colours, it means the gene contains the same information, 

example: both contain the information for blond hair.

When the colours differ, it means  the information in the gene is different. These are variants of the gene

example: one contains information for blond hair, the other for  ginger hair

Sexual reproduction

• Sperm/egg cells are made during a special cell division: meiosis. 
• Meiosis randomly splits all chromosome pairs, giving each daughter cell only 1 of each pair.
• Lots of different chromosome combinations are possible
• During fertilization two sex cells combine, creating new chromosome pairs

During fertilization a spermcell and egg cell combine.

This combines the single genes into pairs of genes

Every body cell has 2 versions of each gene.

Meiosis creates cells that only have 1 version of each gene

Sex

• Decide by X, Y chromosome
• XX = female
• XY = male
• Intersex : XX or XY
• Why is YY impossible?

Male or female?

Male

Female

Sperm

Egg cells

Chromosomes of father

Chromosomes of mother

fraternal twins

• Two egg cells are released at the same tim (2 ovulations happen)
• Both are fertilized by sperm cells
• The genotype is different (These twins don't have to look alike, their sex can be different)

Identical twins

• 1 egg cells is released and fertilized (1 ovulation 1 fertilization)
• During the first cell divisions, the cells split into 2 separate clumps.
• Every clump of cells develops into a child.
• The genotype is identical (these twins have the same DNA, their sex is the same, they will look alike)
  

What you should do: U5 B2

• Pages  106-113
• Asgmt  1-9

OR challenge

• Asgmt 6-11

Done with the above?

• Work on the next chapter(s)
• Learn for the test 
• Make other homework
• Read a book

Zs = Working in Silence

• No asking questions
• Silent, don't disturb anyone
  
• Stay at your  desk

What you should do: U5 B2

• Pages 106-113
• Asgmt 1-9

OR challenge

• Asgmt 6-11

Done with the above?

• Work on the next chapter(s)
• Learn for the test 
• Make other homework
• Read a book

Zw = Working with whispering

• Teacher is available for questions
• Only whisper with the student next to you
• Stay at your  desk

The DNA of a brother and sister is being compared.
Explain: Why is it logical that their DNA is very similar?

Tidy Duty

3 people each lesson

• Desks: empty and straight
• Chairs:  underneath the desks OR end of day: on the desks
• Floor: no rubbish