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Biology Finals > Module 2 > Flashcards

Module 2 Flashcards

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1
Q

Developed the principles of inheritance by experimenting on pea plants; Austrian monk

A

Gregor Mendel

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2
Q

Traits are determined by discrete units called factors (later known as genes). These factors come in pairs, one inherited from each parent.

A

Particulate Inheritance (Mendel’s Conclusions)

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3
Q

In a pair of genes, one form (dominant) can mask the expression of the other form (recessive). The recessive trait only appears in the offspring if inherited from both parents.

A

Dominance and Recessivity (Mendel’s Conclusions)

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4
Q

During gamete formation (sperm and egg cells), the alleles (different versions of a gene) in a gene pair segregate, with only one allele going into each gamete. This ensures that offspring inherit one allele from each parent.

A

Law of Segregation (Mendel’s Laws)

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5
Q

Gene pairs for different traits assort independently during gamete formation. The inheritance of one trait does not influence the inheritance of another. (This applies to genes located on different chromosomes)

A

Law of Independent Assortment (Mendel’s Laws)

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6
Q

When an organism inherits unlike alleles (heterozygous), the phenotype (observable trait) is usually determined by the dominant allele. The recessive allele remains hidden but can be expressed in the offspring if inherited from both parents. However, Mendel also acknowledged exceptions to complete dominance, noting incomplete dominance (where both alleles are partially expressed) and codominance (where both alleles are fully expressed).

A

Law of Dominance (Incomplete Dominance and Codominance are refinements) (Mendel’s Laws)

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7
Q

Mendel’s Laws

A
  1. Law of Segregation
  2. Law of Independent Assortment
  3. Law of Dominance (Incomplete Dominance and Codominance are refinements)
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8
Q

Somatic cells (body cells) in an organism are _______ , meaning they contain two complete sets of chromosomes, one from each parent.

A

Diploid

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9
Q

are haploid, containing only one set of chromosomes. This reduction in chromosome number, achieved through meiosis (cell division), allows for the creation of genetically diverse offspring during fertilization.

A

Gametes

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10
Q

Types of Zygosity

A
  1. Homozygous Dominant (HH)
  2. Heterozygous (Hh)
  3. Homozygous Recessive (hh)
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11
Q

An organism inherits two dominant alleles

A

Homozygous Dominant (HH)

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12
Q

An organism inherits one dominant and one recessive allele

A

Heterozygous (Hh)

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13
Q

An organism inherits two recessive alleles

A

Homozygous Recessive (hh)

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14
Q

basic units of heredity, located on chromosomes and composed of DNA.

A

Gened

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15
Q

is the observable expression of the genotype, influenced by both genes and environmental factors.

A

Phenotype

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16
Q

refers to its complete genetic makeup, including all the alleles it carries.

A

Genotype

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17
Q

are a visual tool used to predict the probability of offspring genotypes and phenotypes based on parental genotypes.

A

Punnett Squares

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18
Q

Modes of Inheritance: Beyond Simple Mendelian Genetics

A
  1. Incomplete Dominance
  2. Codominance
  3. Polygenic Inheritance
  4. Sex-linked Inheritance
  5. Pleiotropy
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19
Q

Neither allele is completely dominant, resulting in a blending of the traits in the heterozygous individual

A

Incomplete Dominance

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20
Q

Both alleles are fully expressed in the heterozygous individual

A

Codominance

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21
Q

Multiple genes contribute to a single trait, with each gene having a small effect. Environmental factors can also influence the final outcome

A

Polygenic Inheritance

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22
Q

Genes located on the sex chromosomes (X and Y) can exhibit unique inheritance patterns. Traits controlled by genes on the X chromosome can be passed from mother to son without being expressed in the mother herself.

A

Sex-linked Inheritance

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23
Q

A single gene can influence multiple traits (e.g., sickle-cell disease affects both red blood cell shape and susceptibility to infection)

A

Pleiotropy

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24
Q

Role of Environment

A
  1. Gene Expression
  2. Phenotypic Plasticity
  3. Environmental Triggers
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25
Q

Environmental factors like diet, light, temperature, and toxins can influence how genes are expressed. They can modify the activity of genes without changing the underlying DNA sequence.

A

Gene Expression

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26
Q

Organisms with the same genotype can exhibit different phenotypes based on their environment. For example, some plants may grow taller in response to increased sunlight.

A

Phenotypic Plasticity

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27
Q

Certain genes may require specific environmental cues to be activated. For instance, some flowering plants only bloom under specific day-length conditions.

A

Environmental Triggers

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28
Q

Inheriting two copies (one from each parent) results in death, usually at the embryonic stage. These alleles are rare as they are typically purged from the population quickly.

A

Dominant Lethals

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29
Q

An organism dies only if it inherits two copies of the allele (one from each parent). These alleles can persist in a population for many generations if carriers (heterozygotes) do not exhibit any negative effects.

A

Recessive Lethals

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30
Q

results in death, usually at the embryonic stage. These alleles are rare as they are typically purged from the population quickly.

A

Dominant Lethals

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31
Q

A dominant allele at one gene can completely suppress the expression of another gene.

A

Dominant Epistasis

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32
Q

The effect of a gene is only expressed when a specific recessive allele is present at another gene.

A

Recessive Epistasis

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33
Q

refers to a single gene having multiple, seemingly unrelated effects on an organism. This phenomenon occurs because a gene product (protein) can play a role in various biological processes. For example, a gene mutation affecting pigment production might influence eye color, skin color, and hair color.

A

Pleiotropy

34
Q

In female mammals, one of the X chromosomes is randomly inactivated in each cell early in embryonic development.

A

X-Inactivation

35
Q

ensures that females generally have the same dosage of X-linked genes as males (who have only one X chromosome).

A

X-Inactivation

36
Q

The inactivated X chromosome is condensed into a structure called

A

Barr body

37
Q

X-inactivation can lead to interesting phenomena like:

A

Carrier females & Calico cats

38
Q

Females who are heterozygous for an X-linked trait (one normal allele and one mutant allele) may exhibit a mix of cells expressing the normal or mutant version of the gene, resulting in a mosaic phenotype.

A

Carrier Females

39
Q

The random inactivation of X-linked genes controlling coat color in cats can lead to the development of a _____ pattern, with patches of orange, black, and white fur.

A

Calico Cats

40
Q

arises when an organism has genetically distinct cell populations due to a mutation occurring at some point during development. This can result in a patchwork of different phenotypes within the same individual.

A

Mosaicism

41
Q

This genetic disorder can cause skin and nerve tumors, and its severity can vary depending on the extent of mosaicism.

A

Neurofibromatosis

42
Q

This condition results in patches of lighter skin and hair due to a mosaic pattern of melanocyte (pigment cell) development.

A

Piebaldism

43
Q

tool used to trace the inheritance of a trait through generations in a family.

A

Pedigree Analysis

44
Q

refers to a group of individuals with genetically identical DNA. These individuals arise from a single parent cell through asexual reproduction.

A

Clones

45
Q

Bacteria reproduce asexually by binary fission, where a single cell divides into two genetically identical daughter cells.

A

Bacterial Fission

46
Q

techniques like budding or grafting can produce clones. These methods involve taking a piece of tissue from a parent plant and using it to generate a new, genetically identical individual.

A

Vegetative Propagation

47
Q

cloning can also be achieved artificially through techniques like

A

Somatic Cell Nuclear Transfer (SCNT) & Embryo Splitting

48
Q

This technique involves separating the blastocyst stage embryo (a cluster of cells) of a fertilized egg into multiple individual embryos. These embryos can then be implanted into surrogate mothers to develop into genetically identical offspring.

A

Embryo Splitting:

49
Q

technique used to create a clone from an adult cell.

A

Somatic cell nuclear transfer (SCNT)

50
Q

Somatic Cell Nuclear Transfer (SCNT) process

A
  1. Nucleus Removal: A nucleus is extracted from a somatic cell (body cell) of the donor organism.
  2. Egg Cell Preparation: An egg cell from a female of the same species is obtained and its own nucleus is removed (enucleation).
  3. Nuclear Transfer: The nucleus from the donor somatic cell is carefully inserted into the enucleated egg cell.
  4. Cellular Reprogramming: The egg cytoplasm reprograms the somatic cell nucleus, essentially reversing its specialized state and returning it to an embryonic state.
  5. Embryonic Development: The reconstructed cell (now containing the donor nucleus) undergoes cell division and begins to develop into an embryo.
  6. Implantation and Birth: The cloned embryo can be implanted into a surrogate mother for gestation and birth.
51
Q

SCNT was famously used to create

A

Dolly the sheep

52
Q

technique used to introduce foreign genetic material (DNA or RNA) into cells.

A

Vector delivery

53
Q

Engineered viruses can efficiently deliver genes into host cells, but safety concerns exist due to the potential for insertional mutagenesis (unintended insertion of the gene).

A

Viral vectors

54
Q

These are circular DNA molecules commonly used in bacteria, and they can be modified to carry foreign genes for delivery into cells.

A

Plasmids

55
Q

These vectors are based on synthetic materials or modified molecules and offer improved safety profiles compared to viral vectors, but their transfection efficiency can be lower.

A

Non-viral vectors

56
Q

refers to the process by which the heritable characteristics of a population change over successive generations. This intricate dance of life shapes the diversity of species we see on Earth today.

A

Evolution

57
Q

There are several key mechanisms driving evolution:

A
  • Natural Selection: This is the prevailing theory of evolution, explained in detail below.
  • Genetic Drift: Random fluctuations in allele frequencies within a population can lead to evolution, especially in small populations.
  • Gene Flow: The movement of genes between populations through migration can introduce new genetic variations.
  • Mutations: Changes in the DNA sequence can create new alleles and fuel the process of evolution.
58
Q

This is the prevailing theory of evolution

A

Natural Selection

59
Q

Random fluctuations in allele frequencies within a population can lead to evolution, especially in small populations.

A

Genetic Drift

60
Q

The movement of genes between populations through migration can introduce new genetic variations.

A

Gene Flow

61
Q

Changes in the DNA sequence can create new alleles and fuel the process of evolution.

A

Mutations

62
Q

system for organizing Earth’s history into major divisions based on significant geological and biological events. It provides a chronological framework for understanding the fossil record and the evolution of life on our planet.

A

Geological Time Scale

63
Q

This is the earliest eon, characterized by the formation of the Earth’s crust and the emergence of the first primitive life forms.

A

Eoarchean Eon

64
Q

This eon saw the rise of the first complex single-celled organisms, the development of photosynthesis, and the formation of the first supercontinents.

A

Proterozoic Eon

65
Q

proposed the theory of inheritance of acquired characteristics, suggesting that traits acquired during an organism’s lifetime could be passed on to offspring. This theory, however, has been refuted by modern genetics.

A

Jean-Baptiste Lamarck

66
Q

credited with developing the theory of evolution by natural selection.

A

Charles Darwin, along with Alfred Russel Wallace

67
Q

theory of evolution by natural selection. This theory proposes that:

A
  • Individuals within a population exhibit variations in traits.
  • Some of these variations are heritable.
  • Individuals with traits better suited to the environment are more likely to survive and reproduce, passing on those advantageous traits to their offspring.
  • Over generations, this process leads to the gradual adaptation of a population to its environment.
68
Q

This is the cornerstone of Darwinian evolution. It explains how heritable traits that enhance survival and reproduction become more common in a population over time.

A

Natural Selection

69
Q

independently developed a theory of evolution by natural selection around the same time as Darwin. Their ideas were presented jointly in 1858.

A

Alfred Russel Wallace

70
Q

though not directly involved in evolutionary theory, laid the foundation of modern genetics with his experiments on pea plants.

A

Gregor Mendel

71
Q

reveal gradual transitions between species, supporting the idea of descent with modification.

A

Fossils

72
Q

allows scientists to determine the age of fossils, placing them within a chronological framework and confirming the order of their appearance on Earth.

A

Radiometric dating

73
Q

Evidences for Evolution

A
  1. Paleontological Evidence (Fossils & Dating Techniques)
  2. Biogeographical Evidence (Distribution of Species)
  3. Comparative Anatomy (Homologous & Analogous Structures)
  4. Embryology (Early Developmental Similarities)
  5. Contrivances (Complex Adaptations)
  6. Vestigial Structures (Remnants of the Past)
  7. Biochemistry and Physiology (Shared Molecular Similarities)
  8. Selection (Direct Observation)
  9. Adaptations (Traits for Survival and Reproduction)
74
Q

permanent changes in the DNA sequence of an organism. They can arise due to errors during DNA replication, exposure to mutagens (environmental factors like radiation), or mobile genetic elements.

A

Mutation

75
Q

refers to the movement of genes between populations. This can occur through migration of individuals or exchange of gametes (pollen, sperm, eggs) between populations.

A

Gene flow

76
Q

During sexual reproduction, chromosomes undergo a process called crossing over, where genetic material is exchanged between homologous chromosomes. This reshuffles existing alleles and creates new combinations of genes in offspring.

A

Recombination

77
Q

random fluctuation of allele frequencies within a population. It can occur due to chance events like sampling error (founder effect) or bottlenecks (sudden population decline).

A

Genetic Drift

78
Q

acts on the existing variations within a population, favoring individuals with traits that enhance their survival and reproduction in a specific environment. These individuals are more likely to pass on their advantageous traits to the next generation, leading to gradual adaptation of the population over time.

A

Natural Selection

79
Q

Humans can also exert selective pressure on populations through

A

Artificial Selection

80
Q

principle that describes a population in which allele frequencies remain constant over generations. This equilibrium state is reached when there are no evolutionary forces acting on the population (no selection, no migration, no mutations, and a large population size).

A

Hardy-Weinberg Equilibrium

81
Q

Mechanisms of Evolution

A

Mutation, Gene Flow, Recombination, Genetic Drift, Natural Selection, Artificial Selection, Hardy-Weinberg Equilibrium

Biology Finals (2 decks)

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