Human Genetics > Topic 2 - Core Concepts > Flashcards

Topic 2 - Core Concepts Flashcards

(70 cards)

Study These Flashcards
1
Q

What is an allele?

A

Different versions of the same gene

Alleles can result in different traits for a given characteristic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define locus (pl. loci).

A

The location of the allele

Loci are specific positions on chromosomes where alleles are found.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does homozygous mean?

A

Both alleles at a locus are the same (e.g., AA or aa)

Homozygous individuals have identical alleles for a trait.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does heterozygous mean?

A

The 2 alleles at a locus are different (e.g., Aa)

Heterozygous individuals have different alleles for a trait.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the phenotype?

A

Observable characteristics based on genotype

Phenotype is the expression of the genotype in an organism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the genotype?

A

Set of genes responsible for a certain trait

Genotype determines the potential characteristics of an organism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is Mendel’s Law of Segregation?

A

During the formation of gametes (sperm or eggs), the two alleles for a gene separate, so each gamete carries only one allele.

This law explains how alleles segregate during meiosis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is Mendel’s Law of Independent Assortment?

A

During meiosis, alleles of different genes segregate independently into gametes, provided the genes are unlinked. (different chromosones or far apart on the same one).

This law applies unless genes are linked on the same chromosome.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a Punnett Square used for?

A

To predict the genotypes and phenotypes of offspring from genetic crosses

Punnett Squares illustrate the probability of inheriting traits.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Fill in the blank: A dominant allele results in a certain phenotype with _______ copy.

A

one

Recessive alleles require two copies to express the phenotype.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a character in genetics?

A

Any detectable phenotypic property of an organism (general feature)

Characters can include traits like eye color or flower shape.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a trait?

A

A specific observable feature

Traits result from the interaction of genes with the environment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does crossing over refer to?

A

The exchange of genetic material between homologous chromosomes during meiosis

This process increases genetic diversity in gametes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is nondisjunction?

A

Failure of chromosomes to separate properly during cell division

Nondisjunction can lead to aneuploidy, an abnormal number of chromosomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is aneuploidy?

A

An abnormal number of chromosomes

This condition can result from nondisjunction events during meiosis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the result of hybridization?

A

Crossing two different true-breeding varieties

Hybridization produces offspring with mixed traits.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the F1 generation?

A

Hybrid offspring of the P generation

F1 generation results from the first cross between two true-breeding parents.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the F2 generation?

A

Offspring produced by mating F1 generation individuals

F2 generation shows the segregation of traits inherited from the F1 generation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does mutation refer to in genetics?

A

Rare events that can change genetic information

Mutations can lead to variations in traits and may affect inheritance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is Cystic Fibrosis characterized by?

A
  • Thickness in body fluids
  • Failure to properly regulate composition
  • Dysfunctional digestive fluids leading to failed nutrient absorption
  • Autosomal recessive inheritance
  • Life expectancy of 41-51 years
  • 80% of deaths due to lung infections
  • Lung transplants can significantly improve outcomes

CFTR stands for Cystic Fibrosis Transmembrane Conductance Receptor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the two types of mutations discussed?

A
  • Gain-of-function (GoF) mutations
  • Loss-of-function (LoF) mutations

GoF mutations often require only one mutated allele to express a new phenotype, while LoF mutations typically require both alleles to be mutated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is an example of an autosomal recessive trait?

A

Albinism

This trait demonstrates segregation patterns in inheritance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is an example of an autosomal dominant trait?

A

Dimples

This trait can be used in practice questions regarding inheritance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

In the gene for cystic fibrosis, what does CF+ represent?

A

The dominant healthy allele

CF- represents the recessive disease allele.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are the **three types of dominance**?
* Complete dominance * Incomplete dominance * Co-dominance ## Footnote Each type describes different interactions between alleles.
26
What is **complete dominance**?
Phenotypes of the heterozygote and dominant homozygote are identical ## Footnote Example: Mendel’s Peas.
27
What is **incomplete dominance**?
Heterozygous phenotype is an intermediate between the homozygous phenotypes ## Footnote Example: Snapdragon flower color.
28
What is **co-dominance**?
Two dominant alleles affect the phenotype in separate, distinguishable ways ## Footnote Example: Human blood group AB.
29
What is **Osteogenesis Imperfecta (OI)** characterized by?
* Brittle bones * Various genetic mutations affecting collagen formation * Can be dominant or recessive ## Footnote Most cases involve a dominant mutation.
30
What is an example of a **co-dominant trait**?
Blood type ## Footnote I^A and I^B alleles are co-dominant.
31
What is an example of **incomplete dominance**?
Snapdragon color ## Footnote Red (C^R) and white (C^W) alleles produce pink (C^R C^W) offspring.
32
What is **epistasis**?
A gene at one locus alters the phenotypic expression of a gene at a different locus ## Footnote This means one gene influences whether another gene is expressed.
33
What is a **polygenic trait**?
A trait influenced by multiple genes at different loci ## Footnote Examples include human height and skin color.
34
What is a **multifactorial trait**?
A trait influenced by multiple factors, including environmental and lifestyle factors ## Footnote Examples include heart disease and diabetes.
35
What is **pleiotropy**?
A single mutation that has multiple effects, producing multiple phenotypes ## Footnote Example: Marfan syndrome.
36
What is **neomorphy**?
A mutation that causes the evolution of a novel feature that was absent from ancestor and is not a modification of a pre-existing structure ## Footnote This can lead to new traits or functions.
37
What does the **Central Dogma** describe?
The process through which genes are used to produce proteins ## Footnote It emphasizes the flow of genetic information.
38
What is the **triplet code**?
Three nucleotide bases on DNA that specify a given amino acid ## Footnote This is fundamental to understanding genetic coding.
39
What is **penetrance**?
The proportion of individuals with a given genotype where the trait shows up ## Footnote Example: Ectrodactyly has 70% penetrance.
40
What is **expressivity**?
How strongly the trait shows up in an individual with the genotype ## Footnote Example: Myotonic dystrophy shows variable expressivity.
41
What is the total number of **chromosomes** in humans?
46 ## Footnote This includes 23 pairs: 22 pairs of autosomal chromosomes and 1 pair of sex chromosomes.
42
What are the four **nucleotide bases** of DNA?
* Adenine (A) * Thymine (T) * Cytosine (C) * Guanine (G) ## Footnote The sequence of these bases encodes genetic information.
43
What determines the **function of a cell**?
The types of genes expressed ## Footnote Only certain genes are expressed, or 'turned on', in each cell at any given time.
44
What can **mutants** change?
Information ## Footnote The sequence of nucleotides determines the protein produced, and changing this sequence can have consequences.
45
What is **vertical transmission** in genetics?
Transfer of genes to the next generation ## Footnote This occurs through the gametes, with each parent contributing to the offspring.
46
What is **horizontal gene transfer**?
Transfer of genes to others within the same generation ## Footnote Mainly seen in bacteria (Prokaryotes and Eukaryotes), such as with plasmid sharing.
47
What does **endosymbiosis** refer to?
Development of mitochondria & chloroplasts in eukaryotic cells ## Footnote This is an example of horizontal gene transfer.
48
What is the traditional view of genetics regarding gene location?
All genetics were nuclear ## Footnote Each parent contributed equally to the offspring's genetic makeup.
49
How many genes are contained in the **mitochondria**?
37 genes ## Footnote These genes are inherited only from the mother.
50
What is a **gene**?
DNA sequence that encodes a functional molecule ## Footnote Gene expression leads to the production of proteins or catalytic RNA.
51
What is a **locus**?
Fixed location of a gene on a chromosome ## Footnote Despite biological variation and crossing-over, gene loci remain the same.
52
What occurs during **crossing over** in meiosis?
Exchanges of DNA between homologous chromosomes at a place where the chiasmata is formed. (During Prophase 1) ## Footnote This process unlinks genes that are on the same chromosome.
53
What are the two important rules in the **Law of Probability**?
* Multiplication Rule * Addition Rule ## Footnote These rules help calculate probabilities of genetic inheritance patterns.
54
What does the **Multiplication Rule** state?
Probability of independent events occurring together is calculated by multiplying their probabilities ## Footnote Key word: 'And'.
55
What does the **Addition Rule** state?
Probability of mutually exclusive events is calculated by adding their probabilities ## Footnote Key words: 'Either', 'Or'.
56
What is the probability of getting **all heads** when flipping 5 pennies?
0.03125 ## Footnote Calculated as (1/2)^5.
57
What is the probability of getting **all heads or all tails** when flipping 5 pennies?
0.0625 ## Footnote Calculated as (1/2)^5 + (1/2)^5.
58
What are the two foundational principles discovered by **Mendel**?
Segregation and Independent Assortment ## Footnote These principles link to events in meiosis.
59
What is the connection between **genotype** and **phenotype**?
Genotype determines phenotype ## Footnote The expression of genes leads to observable traits.
60
What is an autosomal trait
Any trait not located on the sex chromosone
61
How do Mendel’s principles link to events in meiosis?
The Law of Segregation corresponds to the separation of homologous chromosomes in Meiosis I. The Law of Independent Assortment results from the random orientation of homologous chromosome pairs at Metaphase I, allowing different allele combinations in gametes.
62
Using a medical condition, explain the difference between incomplete penetrance and variable expressivity.
Incomplete penetrance: Not all individuals with the disease genotype show the disease phenotype. Example: Some people with a dominant mutation for polydactyly have a normal number of fingers. Variable expressivity: All individuals show the disease, but severity differs. Example: Neurofibromatosis type 1 ranges from mild skin spots to severe tumors.
63
“Character is to trait what gene is to allele.” Explain this statement.
Genes determine alleles; characters determine traits.
64
What is the connection between genotype and phenotype?
A phenotype is the observable trait produced by the genetic makeup (genotype)
65
How can the human body produce ~200 distinct cell types if all somatic cells have the same DNA?
Transcription factors Epigenetic modifications (DNA methylation, histone modification) Cell-specific gene regulation
66
How can a change in DNA sequence lead to a heritable disease?
A mutation can: Alter protein structure or function Change gene regulation Affect RNA splicing or stability If the mutation occurs in gametes, it can be passed to offspring, causing a heritable disorder.
67
What does it mean for genes to be “linked”? How can genes become unlinked?
Linked genes are located close together on the same chromosome and tend to be inherited together. Genes can become unlinked through crossing over during Prophase I of meiosis, which exchanges DNA between homologous chromosomes.
68
What does haplosufficient mean?
A gene is haplosufficient when one functional allele is enough to produce a normal phenotype. → 50% of the normal gene product is sufficient.
69
What does haploinsufficient mean?
A gene is haploinsufficient when one functional allele is NOT enough to produce a normal phenotype. → Reduced gene dosage causes an abnormal phenotype.
70
What does Dominant Negative mean?
A mutant allele whose gene product (protein) interferes with that of the normal copy, preventing it from working properly
Human Genetics
flashcards
Decks in class (21)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions