Principles of Inheritance

Question 1

Describe the sources of individual genetic variation.

Answer 1

Individual genetic variation arises from mechanisms such as mutations, genetic recombination during meiosis, and random assortment of chromosomes during gamete formation.

Question 2

Define the terms genotype and phenotype.

Answer 2

Genotype refers to the genetic makeup of an individual, while phenotype refers to the physical characteristics resulting from that genetic makeup.

Question 3

Describe the different patterns of inheritance.

Answer 3

Patterns of inheritance include autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, and codominance.

Question 4

True or False: Genotype refers to the genetic makeup of an individual, while phenotype refers to the physical characteristics resulting from that genetic makeup.

Answer 4

True

Question 5

What is necessary for growth in living organisms?

Answer 5

Cell division is necessary for growth.

Question 6

True or False: Each cell has the entire DNA blueprint for life in its chromosomes.

Answer 6

True

Question 7

What are the main stages of the cell cycle?

Answer 7

The main stages of the cell cycle are:
Interphase
G1 (cell growth and preparation for DNA synthesis)
S (DNA replication)
G2 (preparation for mitosis)

Mitosis
Separation of replicated chromosomes into two daughter nuclei

Cytokinesis
Division of cytoplasm between two daughter cells

Question 8

What are chromosomes made of?

Answer 8

Chromosomes are made of chromatin, which consists of DNA (40%) and protein (60%).

Question 9

What is required for DNA replication during the S phase?

Answer 9

DNA replication during the S phase requires:

Parental DNA molecules (something to copy)

Enzymes (something to do the copying)

Building blocks (nucleotides)

Question 10

Describe the role of DNA polymerases in DNA replication.

Answer 10

DNA polymerases are specific enzymes that:

Accurately match existing DNA bases with complementary
nucleotide bases

Have proofreading abilities to correct mismatched bases

Link nucleotides together

Add new bases only to the 3’ end of existing strands

Require a primer to begin synthesis

Question 11

What are telomeres and what is their function?

Answer 11

Telomeres are repetitive sequences at the ends of chromosomes that allow accurate replication of the entire chromosome strand. They are associated with the ability of cells to divide and are involved in cell aging.

Question 12

True or False: Telomerase activity is high in most adult non-sex cells.

Answer 12

False. Telomerase activity is low in most adult non-sex cells.

Question 13

What are the stages of mitosis?

Answer 13

Prophase - Chromosomes condense and become visible, and the nuclear membrane disappears.

Metaphase - Spindle fibers align chromosomes along the middle of the cell nucleus.

Anaphase - Sister chromatids separate at the centromere and move apart.

Telophase - Nuclear membrane forms around each set of sister chromatids, forming two new nuclei, and chromosomes begin to uncoil.

Question 14

What is cytokinesis and what does it result in?

Answer 14

Cytokinesis is the division of the cytoplasm and the partition of the cell, resulting in two new daughter cells, each with one nucleus.

Question 15

What is apoptosis and what roles does it play?

Answer 15

Apoptosis is programmed cell death that occurs under normal physiological conditions. It plays roles in:

Normal cell turnover

Homeostasis of the body’s cell population

Embryonic development (e.g., formation of fingers and toes)

Induction and maintenance of immune tolerance

Pruning of the nervous system

Question 16

What are some types of cells with different cell cycle rates?

Answer 16

Cells that rarely or never replicate: skeletal muscle cells, neurons, mature red blood cells.
Cells with years between divisions: smooth muscle cells.
Cells that can continually replicate: epidermal cells, stem cells.

Question 17

True or False: Mutations are always harmful.

Answer 17

False. Mutations can have no effect, be harmless, or even improve cell function, although some mutations are pathogenic and harmful.

Question 18

What causes mutations and what are their potential effects?

Answer 18

Mutations can be induced by exposure to mutagens (e.g., heat, UV radiation, chemicals, microorganisms) or can occur spontaneously due to unrepaired errors during DNA replication, mitosis, or meiosis. Effects of mutations can include:

No effect (silent mutation)

Harmless changes, such as production of new alleles or improved cell function

Pathogenic changes, such as decreased cell function, defective proteins and enzymes, or cell death (lethal mutations)

Question 19

True or False: DNA replication is ‘semi-conservative’ because each new DNA molecule consists of one original strand and one new strand.

Answer 19

True

Question 20

How is cancer related to mutations and cell cycle control?

Answer 20

Cancer results from gene mutations and loss of cell cycle control. Mutations in proto-oncogenes can cause them to become oncogenes, leading to uncontrolled cell growth and proliferation.

Question 21

What are the stages of development of normal cells?

Answer 21

The stages of development of normal cells are:

Replication
Growth
Determination
Differentiation

Question 22

What is cell differentiation and how is it regulated?

Answer 22

Cell differentiation is the process by which a cell becomes specialized to perform a specific function. It is regulated by:

Selective gene activation

Selective gene repression

Different combinations of gene activity at different times during development

Mainly regulated by cell signaling molecules