DNA Lesson 5 Gene expression

• Biologie
• Middelbare school
• vwo
• Leerjaar 4

DNA

Lesson 5 

Gene expression

DNA Lesson 5 Gene expression

Gene regulation in eukaryotes/prokaryotes, gene expression, cell differentiation, epigenetics

Key words

Eukaryotes

Prokaryotes

Stem cells

Gene expression

Cell differentiation

Epigenetics

Endosymbiosis theory

Time

Prokaryote

No nucleus

Circular DNA: no telomeres

DNA in tangle ánd plasmids (small circular DNA)

Small ribosomes

Binary fission

Eukaryote

Yes nucleus

Linear DNA: yes telomeres

DNA in nucleus, mitochondria and chloroplasts

Big ribosomes

Mitosis and meiosis

Fast!

No processing

Prokaryotic cells lack a nucleus. Therefore, the genes in prokaryotic cells are:

1. all expressed, all of the time
2. transcribed and translated almost simultaneously
3. transcriptionally controlled because translation begins before transcription ends
4. B and C are both true

Gene expression

Gene expression = the process by 

which the information encoded in 

a gene is turned into a function. 

This mostly occurs via the 

transcription of RNA molecules 

that code for proteins.

Stem cells

Embryonic stem cells can  develop in all types of cells. When a stem cell divides into two daughter cells one of the cells specializes, the other one stays a stem cell.

Stem cells influence each other because their regulator genes can be switched on or off. If they are switched  'on' then proteins are formed that switch other genes on or off.

Cell differentiation

Cell differentiation = the process by 

which dividing cells change their 

functional or phenotypical type. It 

involves a switch from one pattern 

of gene expression 

to another.

Barbapapa: "kunnen worden wat ze willen worden"...

Genetics 

Genetics = the science of genes and how traits are passed on from one generation to the next. 

Epigenetics p. 392/393

Epigenetics = the study of how your behavior and environment can cause changes that affect the way your genes work. Unlike genetic changes, epigenetic changes are reversible and do not change your DNA sequence, but they can change how your body reads a DNA sequence. So...

1. NO change in A,C,T or G order, but...

2. DNA can NOT be transcribed onto mRNA

DNA can not be transcribed into mRNA

Epigenetics: A,C,T or G sequence is not changed

How come DNA can not be transcribed?

- DNA Methylation

- Histone modification

- Non-coding RNA

... these traits are also passed onto offspring and often reversible

(Not in the test)

Even though your body changes and you develop new physical and behavioral characteristics, your _______ never changes.

1. archetype
2. phenotype
3. appearance
4. genotype

The process by which a cell directs a gene to make a certain protein is called

1. Gene expression
2. DNA extraction
3. Chromosome assembly
4. Genetic modification

Gene expression refers to

1. the molecular structure of DNA
2. the process by which protein manufactures DNA
3. the process by which genetic information in the form of DNA is converted into a gene product, such as an enzyme, through a series of chemical reactions
4. the fact that biological processes rely on chemical reactions

Which of these statements is true about a specialised cell?

1. The cell has only the genes it needs for its function
2. The cell has a complete set of genes and all of these genes are expressed
3. The cell has a complete set of genes but only a fraction of these genes are expressed

Different proteins can be expressed from one gene as a result of what?

1. Alternative RNA splicing
2. DNA replication
3. Translation

How can a person's muscle cells have the same exact DNA sequences as their nerve cells even though they look and perform completely different?

1. the two different cells become mutated
2. the proteins expressed in every cell are different
3. they have different DNA in the two types of cells
4. the genome of the different cells change

Epigenetics is most concerned with...

1. changes in a person’s genotype resulting from environmental influences
2. the expression of a particular gene as influenced by external inputs
3. environmental influences on gene expression over experiential influences
4. the heritability of genotypes that have been altered over multiple generations

What are epigenetic modifications?

1. DNA methylation
2. The removal of nucleosomes from the DNA
3. The addition of more nucleosomes to the DNA
4. Mutation of the DNA sequence

Which of the following is/are true of epigenetic changes?

1. DNA sequences is not changed
2. Move histones to open or close a chromosomal region
3. Are sometimes reversible
4. All of the above

Remember...

Gene expression can be regulated by a variety of factors, including epigenetic modifications and transcription factors. Changes in gene expression can trigger differentiation and determine the fate of a cell...

Homework

Answer the questions on worksheet Lesson 5 in Classroom