Genetics Chapter 6

Question 1

Extranuclear Inheritance

Answer 1

Traits are inherited through genes that are not in the nucleus, but are in other organelles

Ex: mitochondria and chloroplast

Question 2

Maternal Inheritance

Answer 2

A form of inheritance wherein the traits of the offspring are maternal in origin due to the expression of extranuclear DNA present in the ovum during fertilization (Inherited from mother)
Pigmentation of a flower solely depends on the MOTHER’S PHENOTYPE
Parental pigmentation has NO EFFECT on the phenotype
Mitochondria provided through the sperm

Question 3

Maternal Effect Inheritance

Answer 3

Only the genotype of the mother controls phenotype of offspring and is based on oogenesis
Genotype of father has no effect
Genotype of offspring has no effect
Controlled by nuclear genes
Phenomenon is due to the donation of gene products that the mother provides to her developing eggs
Explained by a process of oogenesis
Maturing animal oocytes are surrounded by maternal cells that provide them with nutrients
These nurse cells are diploid, whereas the oocyte becomes haploid

Question 4

Chloroplast genomes

Answer 4

found in nucleoids
Circular chromosomes
The nucleoid may contain many copies of the one chromosome
There may also be multiple nucleoids
The main function of chloroplasts is photosynthesis
The genetic material in chloroplasts is cpDNA

Question 5

Chloroplast Inheritance

Answer 5

Has maternal inheritance
The organelles are inherited only through the egg cytoplasm
Sperm do not transmit chloroplasts however, there are exceptions to this rule
Gymnosperms have paternal inheritance
Some angiosperms have biparental inheritance

Question 6

Mitochondria genomes

Answer 6

The main function of mitochondria is oxidative phosphorylation to produce ATP
Single circular chromosome
Contained within the nucleoid
The genetic material in mitochondria is referred to as mtDNA
Mitochondrial inheritance mechanism depends on species

Question 7

Human mitochondrial diseases and two mechanisms of mitochondrial disease

Answer 7

1.Transmitted from mother to offspring via the egg
Follow a strict maternal inheritance pattern
2. Mutations can occur in somatic cells during aging
Mitochondria are especially susceptible to DNA damage from free radicals
Typically, chronic degenerative disorders affecting cells that need high levels of ATP (Nerve and muscle cells)
Methylenetetrahydrofolate reductase (MTHFR)

Question 8

Endosymbiosis theory

Answer 8

Mitochondria and chloroplasts originated from bacteria that took up residence within a primordial eukaryotic cell
Chloroplasts originated from cyanobacteria
Mitochondria originated from Gram-negative nonsulfur purple bacteria

Endosymbiosis theory is supported by several observations
Organelles have circular chromosomes (like bacteria)
Organelle genes are more similar to bacterial genes than to those found within the nucleus
During the evolution of mitochondria and chloroplasts, most genes have been lost or transferred to the nucleus

Question 9

MZT: maternal to zygotic transition

Answer 9

Maternal effect genes important in early embryogenesis
Regulated by a protein in the oocyte or mRNA

Example - cell division, cleavage pattern, body axis
Accumulation of maternal proteins before fertilization allows development to proceed very quickly after fertilization

Question 10

Concordance

Answer 10

degree to which a disease is inherited, should be higher in identical twins

Question 11

Locus heterogeneity

Answer 11

when mutations in different genes cause the same disease

Question 12

Autosomal recessive disease

Answer 12

cystic fibrosis

Question 13

Autosomal dominant disease

Answer 13

huntington’s disease

Question 14

X-linked recessive disease

Answer 14

hemophilia (problems with blood clotting

“the royal disease”

Question 15

X-linked Dominant disease

Answer 15

vitamin D deficiency with rickets

Question 16

Inheritance patterns that arise from maternal effect break which rule of Mendelian inheritance?

Answer 16

the law where expression of genes in the offspring directly influences their traits

Question 17

Which statements are true for genes that follow a Mendelian inheritance pattern?

Answer 17

The genes are passed unaltered from generation to generation.

The genes obey the law of segregation.

The genes assort independently.

Expression of genes in the offspring directly influences their traits.

Question 18

Inheritance patterns that arise from epigenetic inheritance break which rule of Mendelian inheritance?

Answer 18

the law in which genes are passed unaltered from generation to generation

Question 19

Which statements regarding the nucleoid structure of chloroplasts are true?

Answer 19

The genome consists of double-stranded DNA.

There may be more than one nucleoid per organelle.

There may be more than one chromosome in the nucleoid.

The genome is circular.

Question 20

Inheritance patterns that arise because genetic material is not located in the cell nucleus break which rule of Mendelian inheritance?

Answer 20

the law of segregation

Question 21

Which of these statements are true for chloroplast genes and proteins?

Answer 21

A typical chloroplast genome is about 100,000 to 200,000 bp in length.

Many chloroplast proteins are encoded by nuclear genes.

Question 22

The type of inheritance that occurs because extranuclear genes are inherited through the cytoplasm of an egg is called

Answer 22

maternal

Question 23

The mitochondrial DNA encodes ______ polypeptides that are important for oxidative phosphorylation, and these are ______ of the proteins involved in that process.

Answer 23

13
some

Question 24

Two kinds of gametes are made such that the distribution of cytoplasmic organelles is unequal in the two gamete types, and organelles are often inherited from one parent, in ——- species.

Answer 24

heterogamous

Question 25

Mitochondria usually contain ______.

Answer 25

multiple chromosomes per nucleoid and multiple nucleoids

Question 26

Which eukaryotic species have been known to exhibit biparental inheritance of mitochondria?

Answer 26

S. cerevisiae

angiosperms

Question 27

The situation where a cell contains a mixed population of mitochondria, with some mitochondria carrying a disease-causing mutation while others do not, is called ———— .Disease symptoms will only be observed if the ratio of mutant to normal mitochondria exceeds a certain threshold value.

Answer 27

heteroplasmy

Question 28

Which types of transmission of mitochondria are used in different eukaryotic species?

Answer 28

paternal inheritance

maternal inheritance

biparental inheritance

Question 29

Which of the following are influenced by maternal effect gene products?

Answer 29

cell division

body axis orientation

cleavage pattern