Chapter 8 The developing cell

Question 1

What is the cell cycle?

Answer 1

Cycle of cell growth, maturity, and division producing 2 genetically identical daughter cells

Highly ordered sequence of events used by somatic cells in multicellular organisms.

Question 2

How long does the cell cycle take for embryo cells?

Answer 2

8-60 minutes

Question 3

What is the duration of the cell cycle for liver cells?

Answer 3

Approximately 1 year

Question 4

What are the main stages of the cell cycle?

Answer 4

Interphase, Mitosis, Cytokinesis

Question 5

What occurs during the G1 phase of interphase?

Answer 5

Cell increases in size & mass; metabolic processes remain active

Includes protein synthesis, hormone production, and respiration.

Question 6

What is the G1 checkpoint responsible for?

Answer 6

Cells check for chemicals needed for replication, DNA damage, cell size, and nutrient sufficiency.

Question 7

During which phase is DNA replicated?

Answer 7

Synthesis (S) phase

Question 8

What happens during the G2 phase of interphase?

Answer 8

Chloroplasts and mitochondria increase in size and number; centrioles replicate

Cell continues to grow and prepares for mitosis.

Question 9

What is mitosis primarily responsible for?

Answer 9

Nuclear division producing 2 genetically identical nuclei.

Question 10

What are the stages of mitosis?

Answer 10

Prophase, Metaphase, Anaphase, Telophase

Question 11

What is cytokinesis?

Answer 11

Equal division of cytosol and organelles, forming 2 genetically identical daughter cells.

Question 12

What is the role of cyclins in the cell cycle?

Answer 12

Control sequence and timing of the cell cycle by activating CDKs.

Question 13

What can mutations in cyclin or CDK genes lead to?

Answer 13

Failure to repair DNA, potentially resulting in cancer.

Question 14

What is the lifespan of erythrocytes?

Answer 14

Approximately 120 days

Question 15

What are chromosomes made of?

Answer 15

One molecule of DNA, found in pairs, carrying hundreds to thousands of genes.

Question 16

What are chromatids?

Answer 16

Parts of a chromosome after semi-conservative replication, genetically identical to each other.

Question 17

What defines homologous chromosomes?

Answer 17

Pairs of chromosomes with same structure and gene sequence, but different origins and alleles.

Question 18

What is the function of telomeres?

Answer 18

Protect chromosomes from damage and prevent fusion with neighboring chromosomes.

Question 19

What happens to telomeres with each cell division?

Answer 19

They shorten, usually by 25-200 base pairs.

Question 20

What is apoptosis?

Answer 20

Programmed cell death in multicellular organisms.

Question 21

What is necrosis?

Answer 21

Unregulated cell death due to trauma, leading to cell membrane rupture.

Question 22

What is the significance of apoptosis during development?

Answer 22

Essential for processes like fetal development and immune system formation.

Question 23

What are stem cells characterized by?

Answer 23

Undifferentiated state, ability to divide by mitosis, and large nuclear:cytoplasmic ratio.

Question 24

What are totipotent stem cells?

Answer 24

Stem cells that can form all cell types in a body, including placental cells.

Question 25

What are pluripotent stem cells?

Answer 25

Stem cells that can give rise to all body cell types but not placental cells.

Question 26

What are multipotent stem cells?

Answer 26

Stem cells that can develop into a limited number of cell types.

Question 27

What occurs during the G0 phase of the cell cycle?

Answer 27

Cells enter a resting state and no longer divide.

Question 28

What happens during cell differentiation?

Answer 28

Cells become specialized and switch off certain genes.

Question 29

What are stem cells that can develop into more than one cell type but are more limited than pluripotent cells called?

Answer 29

Multipotent stem cells ## Footnote Examples include adult stem cells in bone marrow and cord blood stem cells.

Question 30

What is multipotency?

Answer 30

The ability of a stem cell to differentiate into discrete cell types ## Footnote For example, a multipotent blood stem cell can differentiate into various types of blood cells.

Question 31

Define totipotent stem cells.

Answer 31

Stem cells that can differentiate into all types of cells within an organism ## Footnote Found in very early embryos before the 50 cell stage in animals and in meristematic tissue in plants.

Question 32

What are pluripotent stem cells?

Answer 32

Stem cells that can give rise to any cells of the organism except extra-embryonic cells ## Footnote Examples include the inner cell mass of the blastocyst.

Question 33

List three uses of pluripotent stem cells.

Answer 33

* Cell replacement therapies * Drug testing in vitro * Studying development of diseases in vitro

Question 34

What characterizes multipotent stem cells in terms of their appearance?

Answer 34

Typically round cells with very little cytoplasm relative to the size of their nuclei ## Footnote Example includes haemocytoblasts in bone marrow.

Question 35

What are some potential future uses for multipotent stem cells?

Answer 35

Possible future use for nervous system diseases such as Parkinson’s and Alzheimer’s disease ## Footnote Also used to treat leukemia and other blood cancers.

Question 36

What is one ethical problem with potential stem cell therapies?

Answer 36

The technology could be used for reproductive cloning ## Footnote Cloning humans raises ethical concerns.

Question 37

What is a significant concern regarding the creation of stem cell lines?

Answer 37

It requires the destruction of human embryos ## Footnote Some believe this constitutes the taking of a human life.

Question 38

What argument is made regarding the rights of human embryos?

Answer 38

Some argue that human embryos have the same rights as individuals ## Footnote They have the potential to develop into an individual.

Question 39

What is a concern associated with stem cell transplants?

Answer 39

They have the potential to produce tumors ## Footnote Tumors can arise from the transplanted cells.

Question 40

What are induced pluripotent stem cells (iPSCs)?

Answer 40

Differentiated adult cells reprogrammed back into pluripotent stem cells ## Footnote These may cause tumors called teratomas.

Question 41

True or False: Embryonic stem cell (ESC) research has produced viable long-term treatments.

Answer 41

False ## Footnote ESC research has not yet yielded viable long-term treatments, unlike some adult stem cell treatments.