Chapter 5 Flashcards

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1
Q

What is the maternal affect

A

Inheritance pattern where the genotype of the mother directly determines the phenotype of her offspring

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2
Q

What is a general explanation of how maternal affect is possible

A

Maturing oocytes are surrounded by maternal cells that provide them with nutrients
The nurse cells are diploid whereas as the oocytes become haploid
Is a mother is heterozygous then the haploid oocyte can develop either the dominant or recessive gene

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3
Q

During maternal affect what happens if the sperm fertilizing the egg has a Dominant allele

A

It is irrelevant because the expression of the sperm will be too late to change early embryonic development

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4
Q

What kind of role does maternal effect genes play in early steps of embryosis

A

Cell division, cleavage pattern
Accumulation of maternal effect gene products before fertilization allows early steps of embryogenesis to pursue very quickly

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5
Q

What is epigenetic inheritance

A

Modification occurs to the nuclear gene or chromosome that alters gene expression

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6
Q

Does epigenetic inheritance change the DNA sequence

A

No and it’s reversible
Expression is not permanently changed over the course of multiple generations

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7
Q

What is the purpose of dosage compensation

A

Offset differences in the number of active sex chromosomes

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8
Q

What is a Barr body

A

Highly condensed structures in interphase nuclei of somatic cells (highly condensed X chromosome)

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9
Q

How does dosage compensation occur in mammals

A

Inactivation of a single X chromosome is females
Chromosome condensation

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10
Q

When does X chromosome inactivation occur

A

In early development
DNA becomes highly compacted and most genes on the inactivated X cannot be expressed

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11
Q

What happens when the inactivated X chromosome is replicated during cell division

A

Both copies remain highly compacted and inactive
It is passed on to all future somatic cells

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12
Q

In mammalian cells how many X chromosomes remain active

A

One
Additional X chromosomes are converted to Barr bodies

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13
Q

What does X chromosome inactivation in mammals depend on

A

The X inactivation center and Xist

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14
Q

What is Xist

A

A gene that makes a gene product

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15
Q

What is Xic

A

A short region on the X chromosome that is termed the X inactivation center
Each X chromosome must have an Xic region for inactivation to occur

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16
Q

What is genomic imprinting

A

When a Segment of DNA is marked and the effect is maintained throughout the life of the organism inheriting the marked dna
Depending on how the genes are marked depends on if the offspring expresses the maternal and paternal inherited allele but not both

17
Q

What is monoallelic expression

A

When a gene is marked and expressed either maternal or paternal inherited alleles but not both

18
Q

What can genetic imprinting involve

A

Single gene
Part of a chromosome
An entire chromosome
All chromosomes of a single parent

19
Q

If genomic imprinting must involve a marking process what is involved

A

An imprinting control region located near the imprinted gene
It is methylated in either the oocyte or sperm but not both

20
Q

What does the ICR contain

A

Binding sites for one or more transcription factors that regulate imprinted genes
For most genes methylation causes inhibition or transcription

21
Q

In regards to methylation what does each parent inherit and how is this maintained

A

Each parent inherits a methylated and unmethylated gene which is maintained in somatic cells

22
Q

When is methylation removed

A

In gamete forming cells

23
Q

What is extranuclear inheritance

A

Inheritance patterns that involve genetic material outside of the nucleus
Also considered cytoplasmic inheritance
Involves the mitochondria and cytoplasm

24
Q

Where is genetic material in mitochondria and chloroplast located

A

Nucleoid

25
Q

What is genome made of

A

Single circular chromosome containing double stranded dna

26
Q

Do chloroplasts or mitochondria tend to have more nucleotides per organelle

A

Chloroplast
Organelles contain more than one nucleotide (by the way)

27
Q

What is the function of the mitochondria

A

Oxidative phosphorylation

28
Q

What is a heterogamous species

A

They produce two kinds of gametes
Female gametes are large and male gametes are small

29
Q

Species with maternal inheritance may sometimes exhibit what

A

Paternal leakage
Paternal parent occasionally provides mitochondria through sperm