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Final exam Flashcards

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Biology 101 flashcards
1
Q

What is the structure, function and properties of carbohydrate?

A

Structure: 1 carbon, 2 hydrogen, 1 oxygen
Function: Fuel substance (bc contains hydrogen)
Properties: they are polar and therefore soluble in water

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2
Q

What is the structure, function and properties of lipids?

A

Structure: Mostly made of hydrogen and carbon but contains a little bit of oxygen
o Fatty acids: the difference between unsaturated and saturated is that the unsaturated has an unsaturated point where the carbon is not bound to the maximum number of hydrogen.
Function:
o Steroids: Can be used as hormones in the body
o Phospholipid: Main component of cell membrane
Properties:
o Lipids in general: water-insoluble (bc don’t have a lot of oxygen) and primarly nonpolar
o Fatty acids: As their chain length increases, they become less water soluble and more solid
o Steroids: Can diffuse (pass-through) cell membrane bc both are non-polar
o Phospholipids: possess dual solubility, they have a polar head (hydrophilic) and a nonpolar tail (hydrophobic)

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3
Q

what is the structure, function and properties of the proteins?

A

Structure: Made of a central carbon atom, attached to an amino group (NH2), a carboxyl group (COOH), and a hydrogen atom. The remaining bond is the R group, also called the side chain, which classifies the type of amino acid. The link between each pair of amino acids in a polypeptide is a peptide bond (formed between the NH2 and the COOH)
Function: Used for structure, as an enzyme, as hormones, receptors, and many more (multipurpose macromolecule)
Properties: All proteins are polymers of amino acids. There are 4 types of amino acids
1. Non-polar (first 10 amino acids)
2. Uncharged polar amino acids (Even if the R group doesn’t have a charge, the oxygen creates a partial charge
3. Negatively charged polar amino acids (acids)
4. Positively charged amino acids (basics)
Both negatively charged and positively charged add reactivity, (ex: galactosidase, the reactive side of the enzyme allows it to react and break the bond). A polypeptide is a string of amino acids whereas a protein is a polypeptide that has folded in 3D shape, which is required for most proteins to be functional.

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4
Q

What is the structure function and properties of nucleic acids?

A

Structure: Made of a nitrogenous base, five-carbon ring-shaped sugar, one to three phosphate groups
Function: Nucleotides form the backbone of nucleic acid. The sequence and arrangement of the base pairs determine the traits.
Properties: Nucleic acids are polymers of nucleotides,
1. DNA: complementary base pairs
o Cytosine-Guanine
o Adenine-Thymine
Forms a double helix
2. RNA: complementary base pairs
o Cytosine-Guanine
o Adenine-Uracil
Exists as a single-strand

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5
Q

What are the functions of the different polysaccharides?

A

Polysaccharides are longer chains formed by the linking of monosaccharides
o Cellulose and chitin are used for structure because of their rigidity. Humans can’t digest cellulose because we don’t have the enzyme for it.
o Glycogen (stored in the liver) and starch (ex: corn, rice, potatoes) are used for fuel

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6
Q

What is the difference between the polysaccharides function?

A

The arrangement of the monosaccharides
o Alpha-polysaccharides (starch and glycogen) are parallel
o Beta-polysaccharides (cellulose and chitin) are perpendicular

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7
Q

Explain how amino acid properties influence the function of proteins.

A
  1. Non-polar amino acids: Do not interact favorably with water, help stabilize the protein’s 3D structure by creating a stable, water-excluded environment.
  2. Uncharged polar amino acids: Interact favorably with water due to their partial charges. Often found on the protein surface, where they can interact with the aqueous environment or other polar molecules.
  3. Positively/Negatively charged amino acids: They are involved in forming ionic bonds, and contribute to protein-protein reactions enabling proteins to form complexes or to bind to charged molecules like DNA or ions.
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8
Q

What are the characteristics, the evolution and role in the ecosystem of bacteria?

A

Characteristics
o Lack of nucleus
o DNA is a single, circular molecule
o One of the smallest organism in the world
o Have no cytoplasmic organelles
o Cytoplasm is viscous
o Contain plasmids (small circles of DNA)
o Have ribosomes
o Have rod or spherical shape
o Have a cell membrane
o Made of phospholipids
o Has a cell wall
o Made of peptidoglycan
o Lack mitochondria
o Have genes arranged in operons
Evolution
o First organisms to have lived on earth
o Fossil and chemical evidence
o Ex: cyanobacteria
Roles in the ecosystem
o Recycle elements such as carbon, oxygen, and nitrogen
o Chemoheterotrophs
o Chemoautotrophs
o Photoheterotrophs
o Photoautotrophs

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9
Q

What are the characteristics, the evolution and role in the ecosystem of archaea?

A

Characteristics
o Lack of nucleus
o DNA is a single, circular molecule
o One of the smallest organism in the world
o Have no cytoplasmic organelles
o Cytoplasm is viscous
o Contain plasmids (small circles of DNA)
o Have ribosomes
o Were isolated from extreme environments (extremophiles)
o Lack mitochondria
o Have genes arranged in operons
o Have proteins called histones
o Lack peptidoglycan
o Have multiple types of RNA polymerase
o Use methionine as the first amino acid placed in proteins
Evolution
o Fossil and chemical evidence
Roles in ecosystem
o Chemoheterotrophs
o Chemoautotrophs
o Photoautotrophs
o Role in the conversion of methane (carbon cycle)
o Role in nitrogen cycle

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10
Q

What are the characteristics, the evolution, and role in the ecosystem of eukarya?

A

Characteristics
o Nucleus
o Have organelles
o Cytoplasm less viscous then in prokaryotes
o Have ribosomes
o Have proteins called histones
o Lack peptidoglycan
o Have multiple types of RNA polymerase
o Use methionine as the first amino acid placed in proteins
o Have a nuclear envelope
o Have multiple linear chromosomes
o Have mitochondria
Evolution
o At first, thought that all eukaryotes were protists
Role in the ecosystem
o Depends on the domain

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11
Q

Identify unique characteristics of eukaryotes

A

They have a nucleus, and organelles, Cytoplasm is less viscous than prokaryotes because the reactions are distributed between the plasma membrane and cytoplasmic solution, they have a nuclear envelope, have multiple linear chromosomes, and they have mitochondria and chloroplast, have a cytoskeleton composed of microtubules, microfilaments, and intermediate filaments, larger and more complex than prokaryotes.

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12
Q

What are the characteristics, evolution and role in ecosystem of protists?

A

Characteristics
o Have a nucleus
o Have multiple linear chromosomes
o Have cytoplasmic organelles including mitochondria and chloroplasts
o Have microtubules and microfilaments
Evolution
o Is the ancestor of fungi, plants and animals
Roles in ecosystem
o Chemoheterotroph
- By engulfing other organisms and digesting them (phagocytosis)
- Absorb organic molecules from the environment (diffusion)
o Photoautotrophs
o Decompose organic matters

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13
Q

What are the characteristics, evolution and role in ecosystem of fungi?

A

Characteristics
o Cell wall made of chitin
o Have a nucleus
o Have multiple linear chromosomes
o Have cytoplasmic organelles including mitochondria and chloroplasts
o Have microtubules and microfilaments
Evolution
o First fungi were aquatic
Roles in ecosystem
o Heterotrophic
- Obtains carbon from nonliving material (saprotroph)
- Obtains carbon from living organisms (symbionts)
o Decompose organic matters (saprotrophs)
o Mycorrizas (association between a fungi and plant roots) (symbionts)
o Lichens (association between fungus and photosynthetic organisms) (symbionts)

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14
Q

What are the characteristics, evolution and role in ecosystem of plants?

A

Characteristics
o Produce chlorophyll as a photosynthetic pigment (exception ghost flower)
o Have cell walls made of cellulose
o Are multicellular
o Sessile (don’t move)
o Alternation of life cycles
o Two multicellular stages (diploid and haploid)
o Have a nucleus
o Have multiple linear chromosomes
o Have cytoplasmic organelles including mitochondria and chloroplasts
o Have microtubules and microfilaments
Evolution
o First adapt to intertidal zones, then spread into shallow, coastal stream
o Charophytes became ancestor of modern plants
Roles in ecosystem
o Photoautotrophs
o Bottom of food chain (producers)
o Together with bacteria and protists, provide nutritional foundation for nearly all ecosystems

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15
Q

What are the characteristics, evolution and role in ecosystem of animals?

A

Characteristics
o Multicellular organisms
o No cell walls
o Cell membrane is in direct contact with one another
o Reproduce sexually or asexually
o Motile at some time in their life
o Store excess energy as glycogen
o Use oxygen to metabolize food through aerobic respiration
o Have a nucleus
o Have multiple linear chromosomes
o Have cytoplasmic organelles including mitochondria and chloroplasts
o Have microtubules and microfilaments
Evolution
o Arose from protist where cells became specialized for specific functions
Roles in ecosystem
o Heterotrophs (consumers)
o At the top of the food chain
o Carnivores or herbivores
o All chemoheterotrophs

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16
Q

What is a chromosome?

A

A chromosome is a DNA molecule with part or all an organism’s genetic material (genome).

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17
Q

What consists of a chromosome?

A

It consists of a short and long arm, a centromere at the center of the chromosome, and telomeres at the end of its tails which shorten with each cell division, and the tails are sister chromatids.

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18
Q

What is inside a chromosome?

A

It consists of many genes, a region of DNA made up of nucleotides, and is the molecular unit of heredity, consisting of many base pairs.

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19
Q

What is the ploidy of a cell?

A

To understand the anatomy of a chromosome, we need to understand the ploidy of a cell, which is the number of copies of each chromosome.

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20
Q

What is n?

A

n is referred to as the number of haploid chromosomes, so the different numbers of chromosomes in a species

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21
Q

Give the ploidy number of haploid, diploid, tetraploid, and polypoid, along with the value of n in humans.

A

Haploid = 1n, diploid = 2n, tetraploid = 4n, polyploid = xn, n = 23 in humans

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22
Q

What is the interphase and what are the stages?

A

A cell cycle phase between 2 mitoses.
It contains the G1, G0, S, and G2.

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23
Q

What is the S phase?

A

It consists of coping DNA and duplicating them, going from 2n to 2N

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24
Q

What is the G1 phase?

A

It takes place before DNA replication, and its objective is to promote the growth of RNA, Proteins and organelles.

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25
Q

What is the G2 phase?

A

Consists of the checkpoint, which DNA is checked for mistakes. Centrioles have doubled into pairs.

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26
Q

What is the G0 phase?

A

It is a cell cycle arrest that occurs between G1 and S, as it stops muscular and nuclear cells from dividing.

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27
Q

What happens in the Prophase?

A

The chromosomes (chromatin fibers) condense, and centrosomes generate the spindle, it is divided into 2 parts. The nuclear membrane starts to break.

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28
Q

What happens in the Prometaphase?

A

Microtubules attach to Kinetochores, as the spindle attaches to the opposite poles. The nuclear envelope disappears.

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29
Q

How are centrosomes connected to the chromosomes?

A

Microtubules attach to the kinetochores, which connect to the centrioles in the centrosomes.

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30
Q

What happens in the Metaphase?

A

46 chromosomes align on the metaphase plate. There is a cell check point to see if the chromosomes are properly aligned and attached to the microtubles

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31
Q

What happens in the Anaphase?

A

Centromeres break, so the chromosomes divide, moving them to opposite poles.

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32
Q

What happens in the Telophase?

A

2 nuclear membranes are formed, creating 2 daughter cells. This happens at the same time as cytokinesis.

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33
Q

What happens in the Cytokinesis?

A

The cleavage furrow cleaves the cytoplasm.

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34
Q

What is aneuploidy?

A

An abnormal number of chromosomes

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35
Q

What are 2 types of disease resulting from of an abnormal number of chromosomes?

A

Trisomy (one more chromosome)
Monosomy (one less chromosome)

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36
Q

What is non-disjunction and misdivision?

A

Non-disjunction occurs during meiosis 1 with 2 gametes with a extra chromosome and 2 with one less, whereas misdivision occur in meiosis 2, and only one extra chromosome more and less, but occurs twice.

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37
Q

Summarize and compare the functions of mitosis and meiosis

A

MItosis: growth, injury repair and replacement of worn-out cells
Meiosis: creating genetic diversity, reproduction

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38
Q

What happens in Prophase 1?

A

There are 3 main events, which are the condensation of chromosomes, synapsis and recombination.
Condensation of chromosomes consists of chromosomes condensing because of DNA replication.
Synapsis consists of the homologous chromosomes coming together.
Recombination consists of the chromosomes exchanging segments.

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39
Q

What happens in prometaphase 1?

A

Microtubules attach to Kinetochores, as the spindle attaches to the opposite poles. The nuclear envelope disappears.

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40
Q

What happens in metaphase 1?

A

chromosomes align on the metaphase plate, they are 2x2.

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41
Q

What happens in Anaphase 1?

A

Centromeres break, so the chromosomes divide, moving them to opposite poles

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42
Q

What happens in Telophase 1?

A

NO nuclear membranes are formed, but still create 2 daughter cells. This happens at the same time as cytokinesis.

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43
Q

What happens after Telophase 1?

A

Interkinesis occurs, as there is no DNA replication (no interphase) between meiosis, as there is no nuclear membrane.

44
Q

What happens in Prophase 2?

A

The chromosomes condense and a spindle forms.

45
Q

Why isn’t there a prometaphase in meiosis 2?

A

There is no nuclear membrane.

46
Q

What happens in metaphase 2?

A

chromosomes align on the metaphase plate, they are 1x1 N.

47
Q

What happens in Anaphase 2?

A

Centromeres break, so the chromosomes divide, moving them to opposite poles

48
Q

What happens in Telophase 2?

A

Nuclear membrane forms, and 4 daughter cells are produced.

49
Q

What are the effects of genetic recombination on chromosomes?

A

It creates genetic diversity

50
Q

Explain the relationship between meiosis, the segregation of chromosomes, and the transmission of alleles from parent to offspring

A

Meiosis produces haploid gametes. During Meiosis I, homologous chromosomes (and their alleles) segregate, ensuring that each gamete gets one allele per gene. Independent assortment and crossing over create genetic diversity by shuffling alleles. When gametes fuse during fertilization, they pass alleles from parents to offspring determining the offspring’s genetic traits.

51
Q

Explain and solve problems on the segregation of chromosomes in gametes

A

Homologous Chromosomes: Pairs of chromosomes (one from each parent) that carry the same genes but may have different alleles.
Law of Segregation: Each gamete receives only one chromosome from each pair, ensuring one allele per gene.
Independent Assortment: Chromosomes segregate independently, leading to diverse combinations of alleles.

52
Q

What is complete dominance?

A

Heritable traits appear unchanged (dominant traits), whereas other traits can disappear (recessive traits), but still come back in future generations.
3-1 phenotypic ratio, 1-2-1 genotypic ratio. (2x2)
3-1 phenotypic ratio, 9-3-3-1 genotypic ratio. (3x3

53
Q

What is codominance?

A

It is the presence of both alleles in the next generation. Both expressed.
What is incomplete dominance?
It is the apparition of a new phenotype in F1, and keeps the 1-2-1 genotypic ratio in F2.

54
Q

What is epistasis?

A

9-3-4 phenotypic ratio, as the non-function of one allele blocks the pigment, leading to a different phenotype.

55
Q

What is the principle of lethal alleles?

A

If an allele is lethal, it will kill the person. If dominant, 0-1 phenotype and genotype. If recessive, 3-0 phenotype.

56
Q

What is the principle of sex-linked alleles?

A

From the X and Y chromosomes, XX for female and XY for males.

57
Q

What are the rules to follow to deduce the pattern of inheritance of a trait and the genotype or phenotype of an individual?

A

Rules:
Does the disease skip generations? If so, then definitely recessive. If not, then probably dominant.
If recessive, are there more men affected than women? If so, then probably X-linked recessive. If not, probably autosomal recessive. * If it X-linked recessive, a mother will always have affected sons, always. If an affected mother has an unaffected son and the trait is recessive, you can rule out X-linked recessive.
Also, it is impossible for a healthy male to get an affected daughter.
If X-linked dominant, an affected father will always have affected daughters, always.
In the presence of a simple pedigree with a few individuals, it is often difficult to rule out possibilities. In such a case, you will probably have to answer “most probably autosomal dominant”, for example.

58
Q

Transcribe DNA sequences to RNA using complementary base pairing

A
  1. Find the template strand (starting from the 3’ end find a start codon TAC and stop codon ATT, ATC, and ACT)
  2. Transcribe the template strand into mRNA from 5’ to 3’ (C-G, A-U. If the presence of introns, transcribe into pre-mRNA, then RNA processing (splicing) into mRNA.
  3. Translate into a polypeptide chain (protein)
59
Q

Differentiate the different types of SNPs, Predict the consequences of different types of mutations on translation and on the cell.

A
  1. Base substitution
    o Missense mutation: Alters the identity of one amino acid, does not change the reading frame, moderate to deleterious effect on the protein
    o Nonsense mutation: Generates an early stop codon, the protein is truncated, severe effects on the function of the protein
    o Silent mutation: Generates no change, the protein remains identical, generally has no effect on the protein.
  2. Frameshift mutation
    o Either an insertion or deletion of an amino acid that will change the reading frame, the remainder protein is changed, a premature stop codon will end translation
60
Q

Explain the potential effect of LCRs

A
  1. Deletion: can cause severe problems if the missing segment contains the gene essential for normal development (ex: one deletion from human chromosome 5 leads to severe cognitive impairment and a malformed larynx, leading to the cri-du-chat)
  2. Duplication: have effects that vary from harmful to beneficial, depending on the genes and alleles contained in the duplicated region. (ex: mammals have genes that encode several types of hemoglobin that are not present in vertebrates such as sharks that have evolved earlier)
  3. Translocation: A segment breaks from one chromosome and attaches to another, non-homologous chromosome (ex: Burkitt Lymphoma is caused by the translocation that moves a segment of chromosome 8 to the end of chromosome 14)
  4. Inversion: A chromosome breaks and then reattaches to the same chromosome, but in reverse order.
    Translocation and inversion have been important factors in the evolution of plants and some animals, including insects and primates.
61
Q

Describe and explain the initiation step of transcription

A

o Transcription factors bind to the promoter and together recruit RNA polymerase
o Each gene contains a promoter that recruits the necessary proteins to initiate transcription
o The promoter contains a DNA sequence, like the TATA box, on which transcription factors will bind(it is present in archaea and eukaryotes)
o Transcription factors are proteins with an active site able to bind specific DNA sequences and then recruit RNA polymerase.
o Several transcription factors are necessary to initiate transcription, once the RNA polymerase binds on DNA, transcription begins

62
Q

Describe and explain the elongation step of transcription

A

o DNA is unwound while new complementary RNA bases are added to the newly formed RNA strand
o A DNA-RNA dimer briefly exists during transcription
o DNA rapidly rewinds to a double-stranded molecule

63
Q

Describe and explain the termination step of transcription

A

o RNA polymerase is released
o In eukaryotes we now have a pre-mRNA it still has to be processed into a translatable mRNA

64
Q

Compare prokaryotic and eukaryotic transcription steps, highlighting the key similarities and differences

A
  • In prokaryotes, there are no transcription factors, RNA binds directly to the promoter and starts transcription.
  • In prokaryotes, genes are transcribed directly into a translatable mRNA, there is no need for pre-mRNA processing
  • Termination in prokaryotes is done either by the mRNA sequence that binds on itself by a complementary sequence forming hairpin, releasing the polymerase by a protein factor that terminates transcription
65
Q

Differentiate the 3 types of RNA found in the cell and give their function

A
  • RNA polymerase I is used to transcribe DNA into rRNA (generates ribosomes)
  • RNA polymerase II is the enzyme used to transcribe protein coding genes (mRNA messenger RNA)
  • RNA polymerase III is the enzyme used to transcribe DNA into tRNA (transferring the amino acids to the ribosomes to build the polypeptide during translation) and some parts of rRNA
66
Q

Describe and explain the three steps of translation

A
  1. Initiation:
    - A specialized methionine bound to a GTP is used as an initiator of translation
    - The ribosome scans the mRNA until it reaches the start codon, establishing the correct reading frame
  2. Elongation:
    - This time, elongation uses amino acids instead of nucleotides
    - The peptidyl transferase enzyme catalyzes the formation of a bond between 2 amino acids
    - The amino acid in the P site will be cleaved from its tRNA
    - Once the amino acid transferase is complete, the ribosome translocates along the mRNA molecule, the polypeptide chain is attached on the most recent amino acid
    - Once the translocation is done, the empty tRNA in the E site is released, The A site is now free to receive the next tRNA corresponding to the next codon
  3. Termination:
    - Termination uses a release factor
    - The polypeptide chain is released
67
Q

Explain how gene expression is regulated in prokaryotes

A

With operons, there are two types of operons:
- Promoter operator : a sequence that controls the expression of the operons
- lacZ (beta-galactosidase): facilitates the cleaving of lactose into galactose, converts lactose to allolactose
- lacY (permease): makes the cell membrane permeable to lactose
- lacA (transacetylase): no idea of its function
o Lac operon
 Lactose absent: repressor is active, binds to the operator so no transcription occurs
 Lactose present: lactose converts to allolactose that inactivates the repressor preventing it to bind to the operator allowing transcription.
o Trp operon
 Trp absent: the repressor is inactive preventing it to bind to the operator allowing transcription
 Trp present: repressor is inactive and gets activated by tryptophan that allows to bind to the operator blocking transcription

68
Q

Explain how gene expression is regulated in eukaryotes

A

Transcriptional control
post-transcriptional control
translational control
Post-translational control

69
Q

What is the transcriptional control in eukaryote gene regulation?

A
  1. General transcription factors: General transcription factors on their own will generate a low level of expression, the more there are, the higher the expression of the gene
  2. Activators: Activators are proteins that bind to the promoter proximal elements and cause a high transcription rate. Other activators can bind to the enhancer region and form a multi-protein complex with activators at the promoter proximal elements, causing a maximum rate expression
  3. DNA methylation: Adds a methyl group onto the bases in the DNA. methylated bases in promoter regions can prevent the binding of transcription factors which turns off the gene
  4. Histone tail acetylation: It changes the charge of the histone tails and results in a loosening of the association of the histones with the DNA
  5. Chromatin remodeling: Chromatin can be remodeled to make the promoter accessible to transcriptional factors and activators, increasing the transcription rate.
70
Q

What is post-transcriptional control in eukaryote gene regulation?

A
  1. 5’ cap: It contains 3 phosphate groups and a guanine. It protects the mRNA from degradation and it is where ribosomes attach at the start of translation
  2. Poly (A) tail: The Poly(A) tail prevents degredation of mRNA when it enters the cytoplasm
  3. Alternative splicing: Exon shuffling occurs. It is a great advantage because it generates protein diversity. They can produce different isoforms with the same gene
71
Q

What is the translational control in gene regulation in eukaryotes?

A
  1. Adjustment of the poly(A) tail: It has an effect of increasing translation or decreasing translation depending on if we increase or decrease the length of the Poly(A) tail prevents degradation
72
Q

What is post-translational control in eukaryotes gene regulation ?

A
  1. Processing (protein activation): Proteins are synthesized as inactive precursors, which are converted to an active form under regulatory control
  2. Polyubiquitination: It adds ubiquitin to the protein which helps tag the doomed (short-lived) protein
  3. Proteasome: Ubiquitin tags identify the doomed proteins so they can get attacked by the proteasome
73
Q

Explain how DNA methylation, histone tail acetylation and chromatin remodeling modulate gene expression

A

DNA methylation enzyme adds a methyl group onto bases in the DNA. Methyled bases in the promoter regions can prevent the binding of transcription factors turning off the gene, Acetylation changes the charge of the histone tails and results in a loosening of the association of the histone with the DNA. This change is called chromatin remodelling where the gene transcription factors and RNA polymerase II are free to bind and initiate transcription.

74
Q

Explain how the 5’cap and the poly A tail help with the translation of a mRNA molecule.

A

The 5’ cap protects the mRNA from degradation and is the site where ribosomes attach at the start of translation. Near the 3’ end, a DNA sequence is transcribed into the pre-mRNA. Protein binds to this polyadenylation signal in the RNA. This signals the RNA polymerase to stop transcription. Then the enzyme poly(A) polymerase adds a chain of adenine nucleotides to the newly created end of the pre-mRNA.

75
Q

Illustrate, understand, and explain how alternative splicing contributes to protein diversity and serves different functions in the cell

A

Alternative splicing allows exon shuffling which generates protein diversity, but it can also lead to disorders. The exons can be assembled in different combinations to produce different isoforms with the same gene. However, depending on the arrangement, it could lead to disorder.

76
Q

What is natural selection?

A

Natural selection is a process in evolution where organisms with traits better suited to their environment have a higher chance of surviving and reproducing. Over time, these advantageous traits become more common in the population.

77
Q

Differentiate natural selection from genetic drift

A

Natural selection isn’t random and survival consists of the fitness traits, whereas genetic drift is random and consists of unknown events (catastrophism) to affect the allele frequencies.

78
Q

Compare and differentiate microevolution and macroevolution, recognize and give examples for each

A

Microevolution is a short-scale evolution from a species, like dogs
Macroevolution is a large-scale evolution that creates species, like wolves and dogs.

79
Q

What are the 5 modes of microevolution?

A

There are 5 types of microevolutions, natural selection, gene flow, genetic drift, nonrandom mating and mutation.

80
Q

What is gene flow?

A

Gene flow occurs when organisms or their genetic material (e.g., pollen, spores, or fertilized eggs) move between populations. When immigrants reproduce, they introduce novel alleles, altering allele and genotype frequencies in the recipient population

81
Q

What is genetic drift?

A

Genetic drift is the random change in allele frequencies due to chance events, especially impactful in small populations. Two notable examples:
What is the bottleneck effect?
Bottleneck effect: A dramatic reduction in population size, such as through disease or disaster, reduces genetic diversity.
What is the founder effect?
Founder effect: A small group of individuals forms a new population, carrying only a fraction of the genetic variation from the original group

82
Q

What is nonrandom mating?

A

Nonrandom mating occurs when individuals choose mates based on specific phenotypes or genetic traits, disrupting random gene distribution. Examples include inbreeding (mating among relatives) and sexual selection (mate choice based on traits like plumage in birds)

83
Q

What is mutation?

A

A mutation is a spontaneous, heritable change in DNA, creating genetic variation that natural selection can act upon. Mutations can be:
Deleterious: Harmful changes of the structure, function, and behavior.
lethal: cause great harm to the organism carrying it
Neutral: No impact on fitness.
Advantageous: Provide a survival or reproductive edge

84
Q

How does sexual selection lead to extreme phenotypes?

A

Females wanted the best from males, so extreme phenotypes were more common, as they wanted to please the females and mate.

85
Q

What are the 3 types of modes of natural selection?

A

There is directional selection, stabilizing selection, and disruptive selection.

86
Q

What is directional selection?

A

Favors one extreme phenotype over others, shifting the population’s trait distribution.

87
Q

What is stabilizing selection?

A

Favors intermediate phenotypes by reducing extremes, maintaining population consistency.

88
Q

What is disruptive selection?

A

Favors extreme phenotypes over intermediates, increasing genetic diversity.

89
Q

What is the biological concept?

A

Defines species as populations that can interbreed and produce fertile offspring in natural conditions. Useful in understanding gene flow and reproductive isolation but limited for asexual organisms

90
Q

What is the Morphological concept?

A

Identifies species based on shared physical traits. Practical for fossils and closely resembling species but doesn’t address evolutionary processes

91
Q

What is the Phylogenetic concept?

A

Defines species as the smallest clusters in an evolutionary tree, based on shared ancestry. Useful for extinct and asexual species

92
Q

Distinguish and describe prezygotic barriers and postzygotic barriers

A

Prezygotic Barriers: Prevent fertilization.
Postzygotic Barriers: Prevent viable or fertile offspring.

93
Q

What are the 5 types of prezygotic isolating mechanisms?

A

The 5 types are ecological isolation, temporal isolation, behavioral isolation, mechanical isolation, and gametic isolation.

94
Q

What is ecological isolation?

A

Species live in different habitats

95
Q

What is temporal isolation?

A

Species reproduce at different times.

96
Q

What is behavioral isolation?

A

Differences in courtship prevent mating.

97
Q

What is mechanical isolation?

A

Mating structures are incompatible.

98
Q

What is gametic isolation?

A

Sperm and egg can’t fuse

99
Q

What are the 3 types of postzygotic isolating mechanisms?

A

The 3 types of postzygotic mechanisms are hybrid inviability, sterility, and breakdown.

100
Q

What is hybrid inviability?

A

Embryos fail to develop, do not live long.

101
Q

What is hybrid sterility?

A

Offspring are sterile (e.g., mules).

102
Q

What is the hybrid breakdown?

A

Later generations show reduced viability or fertility

103
Q

What are the 3 types of speciation?

A

Allopatric, Parapatric, Sympatric.

104
Q

What is Allopatric speciation?

A

Definition: Occurs when a physical barrier separates populations, preventing gene flow. Over time, genetic drift, mutation, and natural selection lead to reproductive isolation.
Example: The uplift of the Isthmus of Panama divided marine organisms, leading to species divergence between the Atlantic and Pacific Oceans
Context: If a mountain range forms and isolates bird populations, they may evolve differently due to varying environmental pressures and genetic drift.

105
Q

What is Sympatric speciation?

A

Definition: Happens when reproductive isolation evolves within a single population without physical separation.
Example: Apple maggots shift their preference from hawthorn to apple trees, leading to mating within subgroups(Unit 4 - Evolution).
Context: If insects begin feeding and mating exclusively on a new type of plant within the same habitat, they might form a new species.

106
Q

What is Parapatric speciation?

A

Definition: Occurs when populations are adjacent but exposed to different environmental conditions, limiting gene flow.
Example: Populations living on different soil types may evolve distinct traits(Unit 4 - Evolution).
Context: A species of grass spreads over areas with different soil pH. Over time, adaptation to the specific soil could result in reproductive isolation

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