1
Q
What are the five nitrogenous bases discovered by Albrecht Kossel?
A
- Adenine
- Thymine
- Guanine
- Cytosine
- Uracil
Received the Nobel prize in 1910 for his work.
2
Q
What is the structure of a nucleotide composed of?
A
- A Nitrogenous base
- A Sugar
- A Phosphate group
3
Q
How many nucleotides can a single DNA molecule contain?
A
Hundreds - even millions.
4
Q
What is the sugar-phosphate backbone of DNA typically compared to?
A
The sides of a ladder.
5
Q
What are the purines in DNA?
A
- Adenine
- Guanine
6
Q
What are the pyrimidines in DNA?
A
- Cytosine
- Thymine
7
Q
What does adenine pair with in DNA?
A
Thymine
Adenine and thymine are bonded with 2 hydrogen bonds.
8
Q
What does cytosine pair with in DNA?
A
Guanine
Cytosine and guanine are bonded with 3 hydrogen bonds.
9
Q
What is the role of hydrogen bonds in DNA?
A
Hold the two strands of DNA together throughout the entire length of the molecule.
10
Q
How do nucleotides connect in a strand of DNA?
A
The phosphate group of one nucleotide connects to the sugar of its neighbor by a phosphodiester bond.
11
Q
What is the function of DNA in cells?
A
DNA stores genetic information that tells cells how to make proteins necessary for various life functions.
12
Q
What is complementary base pairing?
A
The specific bonding between cytosine and guanine (3 hydrogen bonds) and adenine and thymine (2 hydrogen bonds) in DNA.
13
Q
Why must DNA strands be antiparallel?
A
To allow hydrogen bonding between the nitrogenous bases, which can only fit together in a specific orientation.
14
Q
What are the four nitrogenous bases found in DNA?
A
- Guanine (G)
- Adenine (A)
- Thymine (T)
- Cytosine (C)
15
Q
What does antiparallel mean in terms of DNA strands?
A
That the strands in a DNA molecule are parallel but oriented in opposite directions.
The 5’ end of one strand pairs with the 3’ end of the other strand.
16
Q
What are the main differences between DNA and RNA?
A
- DNA:
- Double-stranded helix
- Contains the sugar deoxyribose
- Thymine (T) as one of its bases
- RNA:
- Single-stranded
- Contains the sugar ribose
- Uracil (U) replaces thymine (T)
17
Q
List the similarities between DNA and RNA.
A
- Both contain nucleotide, phosphate, and pentose sugar structures.
- Both use adenine, guanine, and cytosine nucleotides.
- Both carry genetic information.
18
Q
Where is DNA stored and processed within the eukaryotic cell?
A
Within the nucleus of the cell.
19
Q
What is the structure of DNA?
A
Double-helix structure
DNA’s double-helix structure allows it to be easily replicated and preserved during cellular division.
20
Q
What are the nitrogenous bases found in RNA?
A
- Guanine (G)
- Cytosine (C)
- Adenine (A)
- Uracil (U)
21
Q
Where are chromosomes located?
A
In the nucleus.
22
Q
What is the difference in the number of chromosomes between gametic and somatic cells in humans?
A
- Gametic cells: 23
- Somatic cells: 46
23
Q
What are chromatids?
A
These are the two symmetrical structures of a chromosome, each containing a single DNA molecule.
24
Q
What is a centromere?
A
It holds together the two sister chromatids in a chromosome.
25
What is a **chromosome**?
A **single molecule of DNA** representing a specific subset of information in a genome.
26
What are **homologous chromosomes**?
Pairs of chromosomes that **carry the same set of genes**.
27
What are **heterologous chromosomes**?
Chromosomes that carry a **different set of genes** of a particular characteristic.
28
What are the **three parts** of a chromosome?
* Centromere
* Arm
* Telomere
29
What is the **chromosome arm**?
The segment of the chromosome **found on either side of the centromere**.
30
What is the **telomere**?
The portion of the **chromosome tip that protects the chromosomal DNA from degradation** and interactions with other chromosomes.
31
What is a **sister chromatid**?
One of the two copies of a single chromosome produced during replication.
32
What is a **diploid** organism?
An organism that has **two copies of each chromosome**, called homologous chromosomes or homologs.
33
What is a **purine**?
A nitrogenous base that has a **2 ring structure**.
34
What is a **pyrimidine**?
A nitrogenous base that has a **single ring structure**.
35
What is an **allele**?
One of two or more **versions of a gene**.
## Footnote
An individual inherits two alleles for each gene, one from each parent.
36
Define homozygous.
**Homozygous**: Two copies of the same allele within one gene.
37
How is **genotype** translated into **phenotype**?
By considering the relationship between alleles to determine the physical expression of traits.
38
What are dominant and recessive genes?
* **Dominant** gene: A trait expressed in the heterozygous state.
* **Recessive** gene: A trait not expressed in the heterozygous state.
39
What is a key characteristic of a **dominant trait**?
It is **expressed in the heterozygous state** and tends to be more prominent in populations.
40
What is a key characteristic of a **recessive trait**?
It is **not expressed in the heterozygous state** and seems to disappear after time in a population.
41
What did Mendel's Second **Law of Independent Assortment state**?
Each genetic trait segregates separately from other genetic traits.
42
What did Mendel's **First Law of Inheritance** state?
Genes on chromosomes are segregated or separated during sexual reproduction (meiosis).
## Footnote
Also known as the law of segregation.
43
How did Mendel **confirm** his First Law of Inheritance?
By crossing pea plants that differed in observable and scoreable traits.
44
What is a **pure-breeding** strain in Mendel's experiments?
A strain that gives offspring with 100% of its given trait when self-pollinated.
45
What did Mendel's **dihybrid cross** experiments demonstrate?
The seed shape and seed color traits would segregate independently of each other.
46
What is a **Dihybrid Cross**?
A cross between individuals that are **heterozygous at two different loci**.
47
What **ratio** did Mendel's Second Law predict in a dihybrid cross?
9:3:3:1
48
Who is known as the **Father of Genetics**?
Gregor Mendel
49
Define the **Purity Law** of Gametes.
It states that only one allele from each parent enters the gamete, making it 'pure'. Newly paired alleles act independently and do not impact or change each other.
50
What are the **three laws** credited to Gregor Mendel?
* Law of Segregation
* Law of Dominance
* Law of Independent Assortment
51
What is the process that happens during meiosis according to Mendel's Law of Segregation?
Segregation occurs between the first and second meiotic cell divisions, where alleles split and are randomly selected from each parent to form the offspring.
52
How does Mendel's Law of Segregation relate to Punnett squares?
Punnett squares showcase how alleles separate during meiosis.
53
What is a **genotype**?
The set of two alleles.
## Footnote
Depicted as 2 letters: BB, Bb, bb
54
What is a **phenotype**?
The trait that can be **seen**.
55
What is a **gene**?
The segment of DNA that **determines the phenotype** or displayed trait.
56
What is a **Punnett square** used for?
To **predict** the likelihood of each possible combination of alleles.
57
What does '**mono**' mean in a monohybrid cross?
One
58
What does '**hybrid**' mean in a monohybrid cross?
Mixed or **blended** in terms of genetics.
59
What does '**F1**' stand for in genetics?
Filial
| Latin for 'sons'
60
How is a **dominant trait** symbolized in genetics?
By capital letters.
61
What is the purpose of **monohybrid crosses** in genetics?
Help determine if a trait is dominant or recessive.
62
How many rounds of monohybrid crosses are usually sufficient to determine if a trait is dominant or recessive?
Usually, two rounds.
63
What is the outcome of a monohybrid cross between two true-breeding, homozygous parents?
An F1 generation where all offspring are heterozygous and identical to the dominant parent.
64
What is the phenotypic ratio in the F2 generation of a monohybrid cross?
3 dominant : 1 recessive.
65
What are the **steps** in performing a monohybrid cross?
1. Determine the genotypes of the parents.
2. Write down the possible gametes for each parent.
3. Arrange the parents' gametes around the edges of a Punnett square.
4. Fill out the offspring squares.
5. Interpret the results.
66
What is the **difference** between a monohybrid cross and a dihybrid cross?
* A monohybrid cross studies the inheritance of a single gene.
* A dihybrid cross studies the inheritance of two genes simultaneously.
67
What is the **purpose** of a dihybrid cross?
To analyze the inheritance of two characteristics or genes at the same time.
68
How did Mendel start his studies on inherited characteristics?
By focusing on singular inherited traits from crosses of his pea plants.
69
What is a monohybrid cross?
The creation of a new generation from two organisms that are hybrids for a single characteristic or trait.
70
Define heterozygous.
**Heterozygous**: Two different alleles at a locus.
71
What is an inheritance pattern where *both dominant genes are expressed* in heterozygous individuals rather than blending?
Codominance
72
What is the advantage of having **two X chromosomes** in females regarding sex-linked traits?
Disadvantageous recessive phenotypes can be masked in a heterozygote.
73
What is a **sex-limited** trait and where are they usually found?
A trait that is only expressed in **one of the sexes**. Typically found on an autosome, although they are just expressed in one sex.
74
What happens when a person inherits **one IA allele** and **one IB allele** for blood type?
They have blood type AB.
## Footnote
When both IA and IB alleles are present, they are co-dominant, resulting in blood type AB.
75
How is the **i allele** different from **IA and IB alleles** for blood type?
It is recessive towards both IA and IB alleles.
## Footnote
The i allele is recessive, meaning it is not expressed when IA or IB alleles are present.
76
What are **multiple alleles**?
*Three or more variations* of a gene.
## Footnote
Traits controlled by multiple alleles include:
* Blood type in humans
* Fur color in animals
77
What is a **polygenic trait?**
A trait in which the phenotype is controlled by more than one gene.
## Footnote
Examples of polygenic traits in humans:
* Eye color
* Skin color
* Height
* Hypertension
* Diabetes
* Schizophrenia
* Asthma
* Cancer
78
What does it mean when **polygenic traits** are considered **multifactorial**?
Multiple genes and/or the environment influence the phenotype.
79
What are **monogenic traits**?
Traits that are controlled by a **single gene**.
80
What is **co-dominant** inheritance?
Both alleles are expressed together in the heterozygous organism.
81
How do polygenic traits contribute to natural selection?
They create a wide variety of phenotypes in a species, increasing the likelihood of a good fit for the environment.
82
What makes polygenic traits **different** from Mendelian traits?
* Polygenic traits are controlled by **multiple genes.**
* Mendelian traits are inherited at a **single gene with two alleles**.
83
Define the characteristics of polygenic traits.
Quantitative, multifactorial, controlled by multiple genes or environment.
## Footnote
Quantitative: Having continuous variation.
84
What is **epistasis**?
The phenomenon of one gene suppressing or interfering with the physical expression of another gene.
## Footnote
Polygenic traits that require the presence of an epistatic gene:
* Hair color
* Eye color
* Skin color
85
What are the **types of epistasis**?
* Recessive epistasis
* Dominant epistasis
86
When does **dominant** epistasis occur?
When there is complete dominance of one gene.
87
What is **recessive** epistasis?
Occurs when recessive alleles on one gene interrupt or mask the expression of another gene.
## Footnote
Example: Albinism
88
What are the **causes** of epistasis?
* Mutagens or physical or chemical influences which can cause a gene to mutate and be broken.
* Recombination during meiosis.
* Nondisjunction during meiosis.
89
How can epistasis be a factor in disease?
It can **worsen the severity of diseases**, such as Alzheimer's, by interacting with other genes to exacerbate the condition.
90
What is **pleiotropy**?
One gene affecting **multiple traits**.
## Footnote
Examples: TBX5 gene codes for T-box 5 protein, affecting upper limbs and heart.
91
What is the **difference** between pleiotropy and polygenic inheritance?
* **Pleiotropy**: one gene affects multiple traits.
* **Polygenic inheritance:** many genes influence one trait.
92
What is **antagonistic pleiotropy**?
When a trait that increases fitness in one area decreases fitness in another.
93
How does antagonistic pleiotropy relate to senescence?
Competing effects of a gene causing traits that enhance fitness earlier in life but lead to age-related disorders and decreased lifespan.
94
What is **senescence**?
The deterioration associated with **aging**.
95
What is the **difference** between antagonistic pleiotropy and normal pleiotropy?
* **Antagonistic** pleiotropy involves traits with competing effects.
* **Normal** pleiotropy involves a single gene affecting multiple traits.
96
Provide examples of pleiotropic diseases.
* Sickle cell anemia
* Phenylketonuria (PKU)
## Footnote
Sickle cell anemia alters the shape of red blood cells so that they are sickle shaped, and can no longer adequately transport oxygen.
Phenylketonuria prevents the breakdown of phenylalanine into tyrosine.
97
What is **cytoplasmic inheritance**?
Inheritance of genes in the cytoplasm of a cell not within the nucleus.
## Footnote
Also known as extranuclear inheritance.
98
What is the distinct feature of cytoplasmic inheritance?
* The female is generally the only contributor toward the inheritance of specific DNA.
* Patterns of phenotypes do not appear as expected in Mendelian laws of inheritance.
99
What are the **three types** of cytoplasmic inheritance?
* Vegetative segregation
* Uniparental inheritance
* Biparental inheritance
100
What is **mitochondrial inheritance**?
Inheritance of genes from mitochondrial DNA, mainly maternal.
101
What organelles contain their own copies of DNA similar to mitochondria?
**Chloroplasts** found in plant cells.
102
How does the inheritance pattern of **mitochondria** and **chloroplasts** differ from nuclear DNA?
They follow the inheritance pattern of cytoplasmic inheritance, not Mendelian genetics.
103
What is **polygenic inheritance**?
It is an inheritance where one characteristic is controlled by two or more genes.
104
When does **uniparental inheritance** occur?
When offspring inherit extranuclear genetic information from a single parent.
105
When does **biparental inheritance** occur?
When extranuclear genetic information is inherited from both parents.
## Footnote
Very rare and can only occur in some species.
106
What is **mitochondrial DNA** also known as?
mtDNA
107
What is **vegetative segregation**?
Random replication and separation of organelles in the cytoplasm during cell division, producing daughter cells with a random sampling of parental cytoplasmic organelles.
108
Why are humans considered **poor model organisms** for the study of genetics?
* Long generation times.
* Inability to make controlled crosses.
* Limited number of offspring.
* Restrictions on genetic manipulation.
109
What do human geneticists study **in the absence** of controlled crosses and genetic manipulation?
* Human genome in its natural context.
* Naturally occurring mutations.
* Family pedigrees.
110
What can be determined by **analyzing pedigrees** in the study of human genetics?
* Whether a genetic condition is dominant or recessive.
* Whether a condition is caused by a gene on the X chromosome or an autosome.
111
What is the **difference** between autosomal and sex-linked conditions?
* **Autosomal** conditions are caused by genes on chromosomes 1-22.
* **Sex-linked** conditions are caused by genes on the X chromosome.
112
Why are **males** more likely to be affected by sex-linked conditions like color-blindness?
Males have only **one X chromosome**, so a single copy of the color-blind allele will determine their phenotype.
113
Why are complex diseases more challenging to study than simple autosomal conditions?
They have contributions from **multiple gene loci** and non-genetic factors, making them more difficult to understand.
114
What method do human geneticists use to study complex diseases due to their multifactorial nature?
Population genetics
115
How do geneticists try to minimize the impact of non-genetic factors when studying complex diseases?
Match the non-genetic factors of affected and unaffected individuals.
116
What type of condition is caused by a **gene on an autosome**?
Autosomal condition
## Footnote
Examples:
* Huntington's disease
* Polycystic kidney disease
* Cystic Fibrosis
117
What is a **pedigree**?
Charts of family histories that show **phenotypes** and **family relationships** of individuals.
118
How are **males** and **females** represented in a pedigree?
* Male represented by a **square**.
* Female represented by a **circle**.
119
What does an **open shape** in a pedigree represent?
Individual **does not** exhibit the trait of interest.
120
What does a **filled-in shape** in a pedigree represent?
Individual **exhibits** the trait of interest.
121
What is a proband in a pedigree?
The first affected family member seeking medical attention.
## Footnote
Marked with an angled arrow labeled with a capital P pointing to the filled in shape.
122
How are family relationships represented in a pedigree?
* **Marriage line** connecting shapes of partners.
* **Vertical line** for children.
* **Divorce** is represented by a break in the relationship line that connects the couple.
123
How are **twins** represented in a pedigree?
By a **bifurcated vertical** line.
## Footnote
Monozygotic twins are represented by connecting the split line with a horizontal line.
124
How is **death** indicated in a pedigree?
By placing a **diagonal line over the symbol** of the deceased individual.
125
How are miscarriages and abortions shown on a pedigree chart?
* **Miscarriage**: Triangle shape attached with a shorter vertical line.
* **Filled-in triangle** indicates the fetus was *affected*.
* A **diagonal line over the triangle** if pregnancy was *terminated*.
126
What is a **carrier** in genetics?
Someone who has one copy of the gene for a genetic condition but also has another gene that keeps them from developing the condition.
127
What is the inheritance pattern for autosomal **dominant** traits?
An individual will develop the condition if they get **a copy of the gene** from either one of their parents.
128
What are **sex-linked traits**?
Traits found on the **X chromosome**.
129
How are carriers identified in a **pedigree for autosomal recessive traits**?
*If two unaffected parents have offspring that are affected*, then the pedigree is showing an autosomal recessive trait.
130
How are carriers identified in a pedigree for **sex-linked traits**?
If there are *affected male children, unaffected female children, and unaffected parents*, then it is most likely a sex-linked trait and the **mother is a carrier**.
131
Describe the **inheritance pattern** of sex-linked traits.
Sex-linked traits often follow a **crisscross** pattern of inheritance.
## Footnote
Affected males pass a sex-linked recessive gene to their daughters, who become carriers of the trait. These carrier females then pass the affected allele to half of their sons and daughters.
132
Explain the difficulty in identifying autosomal recessive conditions in pedigrees.
Most of the recessive alleles remain hidden in unaffected carriers and only become apparent in a small number of family members, often separated by generations.
133
What is a pattern of inheritance where heterozygous individuals will *display a blend of traits*?
Incomplete dominance
134
What is true of genes that are said to be **linked**?
The genes are found on the **same chromosome**.
135
What is **epigenetics**?
The study of how **environmental factors** influence heritable traits.
## Footnote
Does not involve changes to the underlying DNA sequence.
MTTC Biology
flashcards
Decks in class (31)
# Cards
-
Foundations of Scientific Inquiry30
-
Designing Scientific Investigations98
-
Laboratory Safety & Scientific Tools72
-
Nature & History of Science68
-
Sources of Genetic Variation36
-
Cell Structure & Function160
-
Cell Transport and Homeostasis102
-
Biomolecules & Cell Chemistry101
-
Energy Transformations in Cells39
-
Energy Pathways in Living Organism100
-
Levels of Biological Complexity52
-
Life Cycles & Development97
-
Mendelian Genetics135
-
Molecular Basis of Heredity97
-
Mutations & Genetic Variation75
-
Genetic Technologies & Applications104
-
Mechanisms of Evolutionary Change72
-
Patterns of Evolution & Biodiversity85
-
Origins of Life & Paleobiology18
-
Classification & Characteristics of Life83
-
Life Cycles, Growth & Reproduction50
-
Anatomy & Physiology of Animals186
-
Anatomy & Physiology of Plants107
-
Homeostasis & Energy Use in Organisms60
-
Human Health & Immunology20
-
Human Population Growth & Diversity18
-
Population & Community Ecology173
-
Energy Flow in Ecosystems125
-
Interactions in Ecosystems124
-
Ethics in Biotechnology68
-
Resource Use & Sustainability18
