BABS2202

Revision Session 2

Learning Outcomes

The Birth of Cells

Explain the role of growth factors in initiating the cell cycle by inducing the expression of transcription factors such as Myc

Recognise the role of embryonic stem cells and the process of differentiation in giving rise to all cells in the body

List and describe the different types of stem cells

Describe the therapeutic use of induced pluripotent stem cells in treating disease

The correct order for the blank boxes in this figure on stimulating cells to grow is:

A. growth factor receptor, growth factor, Ras, Myc

B. growth factor, growth factor receptor, p53, Myc

C. growth factor, growth factor receptor, Myc, p53

D. growth factor, growth factor receptor, Myc, Ras

E. growth factor, growth factor receptor, Ras, Myc

Which of the following statements about stem cells is true?

A. Adult stem cells can only differentiate into a limited number of cell types within their tissue of origin.

B. Embryonic stem cells are derived from the placenta.

C. Induced pluripotent stem cells (iPSCs) are derived from embryonic tissues.

D. Stem cells are incapable of self-renewal.

E. Hematopoietic stem cells can differentiate into any cell type in the body.

Which statement about totipotent cells is false?

A. Most versatile of the stem cell types

B. Have the potential to give rise to any and all cells

C. Cannot give rise to an entire functional organism

D. The fertilized egg is totipotent

E. The first few cell divisions in embryonic development produce totipotent cells

Learning Outcomes

Lecture 6: End of the Cell Cycle

Recognise that cells can die by two different mechanisms and what distinguishes each

List the differences between apoptosis and necrosis

Describe the process of apoptosis and the differences between the intrinsic and extrinsic pathways

Outline the role that caspases play in apoptosis and their mechanism of action

Which of the following best describes apoptosis?

A. It is a form. of programmed cell death.

B. It results from cellular injury or trauma.

C. It causes inflammation in surrounding tissues.

D. It is characterized by cell swelling and rupture.

E. It primarily occurs in response to infection.

How is apoptosis involved in normal embryological development?

A. Apoptosis removes parts of the parent DNA from the embryo.

B. Apoptosis is used to provide nutrients to developing cells.

C. Unnecessary parts of the body that normally develop in the embryo are removed with apoptosis.

D. Overall brain development is inhibited by apoptosis to keep the embryo safe.

Which cellular organelle plays a crucial role in initiating apoptosis?

A. Endoplasmic reticulum

B. Golgi apparatus

C. Lysosome

D. Mitochondrion

E. Nucleus

Which of the following is a key characteristic of the extrinsic pathway of apoptosis?

A. It is initiated by DNA damage within the cell.

B. It involves the release of cytochrome c from the mitochondria.

C. It is triggered by extracellular death ligands binding to death receptors on the cell surface.

D. It primarily activates the intrinsic apoptotic pathway through Bcl-2 family proteins.

E. It is independent of caspase activation.

Learning Outcomes

Lecture 7: Cancer

Recognise that cancer is induced by an accumulation of mutations in a cell, all related to cell growth

Describe how mutations in proto-oncogenes cause them to be activated oncogenes and how this can lead to cancer

Describe the role of tumour suppressor genes, such as p53, and how mutations in them can lead to cancer

Understand that loss of DNA repair function, or the action of tumour-causing viruses, can also contribute to cancer

Cancer is more common in older people because:

A. Their immune systems have degenerated

B. The supply of certain hormones declines with age

C. A change in the rate of cell replacement takes place

D. They have accumulated more mutations

E. Their bodies are unable to adjust to the changing environment

Which of the following explains how apoptosis is related to cancer?

A. Cancer cells cause excessive apoptosis in surrounding cells to make room for more cancer cell growth.

B. Cancer is an example of uncontrolled apoptosis.

C. Cancer cells are formed when necrosis occurs instead of apoptosis.

D. The cues that would trigger apoptosis have failed in cancer cells

Which of the following best defines an oncogene?

A. An oncogene codes for a cell cycle control protein.

B. An oncogene codes for a mutated form. of a protein that is involved in DNA replication.

C. An oncogene codes for a protein that prevents the cell from undergoing apoptosis.

D. An oncogene is a dominantly expressed mutated gene that gives a cell a growth or survival advantage.

E. To create an oncogene two mutation events are required.

Which of the following statements about the Rb tumour suppressor protein is correct?

A. Rb is activated when phosphorylated by Cdk.

B. Rb binds the transcription factor E2F and thus prevents the cell from entering S phase until a mitogenic signal is received.

C. Rb is a transcription factor.

D. When a mitogenic signal is received, Rb binds the transcription factor E2F and thus stimulates the cell to enter S phase

Learning Outcomes

Lecture 8: Alternative Cell Cycles

Describe the process of meiosis and its purpose

Describe the formation of male and female gametes

Understand the consequences of meiotic disjunction

Explain genomic imprinting and X-chromosome inactivation

Which of the following correctly describes how mitosis and meiosis are different?

A. The number of chromosomes is doubled after mitosis, while the number of chromosomes remains the same after meiosis.

B. Sister chromatids separate during meiosis but not mitosis.

C. DNA replication occurs prior to mitosis but not meiosis.

D. Mitosis produces genetically identical daughter cells, while meiosis produces genetically unique daughter cells.

Which of the following correctly describes how meiosis I and meiosis II differ?

A. Genetic material is exchanged between homologous chromatids during meiosis II but not meiosis I.

B. Pairs of homologous chromosomes are separated during meiosis I, while sister chromatids are separated during meiosis II.

C. Meiosis I produces diploid daughter cells, while meiosis II produces haploid daughter cells.

D. Cytokinesis occurs following meiosis II but not meiosis I.

What is the result of this process (found on right side of the arrow)?

A. An embryo containing half of the genetic information

B. A zygote containing a complete set of genetic information

C. A gamete containing a complete set of the genetic information

D. A blastocyst containing half of the genetic information

Nondisjunction can occur if _____________ chromosomes fail to separate during meiosis I.

A. Homologous

B. Heterozygous

C. Defective

D. Sex

E. Autosomal

Even though humans are approximately 99.9% identical in their genetic makeup, incredible variation is seen among individuals of the species. This genetic variation is greatly influenced by the process of meiosis.

Of the following events that occur during meiosis, which contributes most to genetic diversity in the human population?

A. Condensation of chromatin during meiosis I

B. Separation of sister chromatids during meiosis II

C. Recombination between homologous chromatids during meiosis I

D. Alignment of sister chromatids at the metaphase plate during meiosis II

Midterm exam – assertion-reason questions

These take the format of a statement, and you must decide if it is true or false, and then provide a reason for your answer.

Each question is worth 2 marks: 0.5 mark for true/false and 1.5 marks for providing a reason.

Example: Pluripotent cells are able to give rise to an entire organism. True or False?

False (0.5 marks). Pluripotent cells can give rise to many cell types but only totipotent cells are able to give rise to an entire organism. (1.5 marks)

Example: The number of gametes produced from a single primordial germ cell by the processes of oogenesis or spermatogenesis is the same. True or False?

False (0.5 marks). During the formation of sperm cells from a single primordial germ cell 4 gametes will be formed, whereas only 1 egg is formed from a single primordial germ cell (and two polar bodies). (1.5 marks)