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Biology 315 > C8 Genetics, Evolution, + Immunity > Flashcards

C8 Genetics, Evolution, + Immunity Flashcards

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1
Q

Locus

A

Position of a gene on a chromosome

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2
Q

Allele

A

Genes occupying the same locus on homologous chromosomes

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3
Q

Homologous

A

Similar chromosomes: have same gene sequence, a pair.
Usually one inherited from the father and one from mother.

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4
Q

Genotype

A

The set of genes possessed by an organism (e.g. BB, Ee, kk)

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5
Q

Phenotype

A

Visible characteristics/physical expression of the genes (e.g. blue eyes, curly hair)

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6
Q

Mitosis

A

Normal cell division
- produces somatic (body) cells
- no change in chromosome number ( stays 2n)

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7
Q

Meiosis

A

Reproductive cell division
- produces gametes (sperm/egg)
- change in chromosome number (2n to n)

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8
Q

Diploid

A

Normal chromosome number for each species (pairs, 2n)

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9
Q

Haploid

A

Half the chromosome number for each species (single, n)

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10
Q

Gamete

A

Sex cell
- sperm/egg
- haploid (n)

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11
Q

Zygote

A

Fertilised cell
- sperm + ovum combined
- 2n (diploid)

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12
Q

Pure breeding

A

Pedigrees
- organisms containing homozygous genes for a trait (BB/bb)

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13
Q

Homozygous

A

Identical genes in a pair (e.g. PP, tt)

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14
Q

Heterozygous

A

Different genes in a pair (e.g. Pp, Tt)

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15
Q

Dominant

A

The gene that masks the other gene in the organism’s phenotype
- written as capital letter (e.g. B, T)

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16
Q

Recessive

A

The gene that is masked by the dominant gene in the organism’s phenotype
- written as lowercase letter (e.g. b, t)

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17
Q

Co-dominant

A

Both genes are equally dominant (e.g. A and B blood groups)

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18
Q

Sex-linked inheritance

A

Traits carried on the X chromosome (more room)
- tend to be recessive

More common in males:
- males only have one: therefore there is no chance of it being masked if it is passed down
- less common in females due to 2x X chromosome

Sons do not share the phenotypes of their fathers:
- must take Y chrom from father
- if father has the trait, will not affect the son

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19
Q

Autosomal trait

A

Trait carried on the non-sex (autosomal) chromosomes
- 22 pairs of autosomal chromosomes in humans, 1 pair sex chromosomes

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20
Q

autosomal inheritance
- what is it
- dominant vs recessive qualities

A

Autosomal inheritance: trait is carried on the autosomal chromosomes (not X/Y)

DOMINANT
- affected individuals carry at least one dominant gene
- non affected individuals must be homozygous recessive (e.g. bb)
- does not skip generations (affected people will be in all generations)
- sometimes the exact genotypes will be unclear (label the possibilities, e.g. BB/Bb)

RECESSIVE
- affected individuals must be homozygous recessive (e.g. bb)
- can skip generations
- people can be carriers but not affected, due to presence of dominant gene

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21
Q

Mutation

A

Random change in a gene or chromosome that alters the way it controls development

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22
Q

Linkage

A

Genes are linked on the same chromosome (search up a pic if unsure)

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23
Q

Trait

A

A characteristic that can be passed down

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24
Q

Hereditary

A

The passing of traits to the next generation

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25
Q

Monohybrid cross

A

A cross involving a single trait (e.g. hair colour)

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26
Q

Dihybrid cross

A

A cross involving two traits (e.g. hair colour and eye colour)

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27
Q

simple/mendelian inheritance

A

occurance of a trait is controlled by a single gene
- dominant and recessive alleles

28
Q

State the 3 generations used in genetics problems.

A
  • P1 parental: og generation
  • F1 filial: offspring from P1
  • F2 filial: offspring from F1
29
Q

Outline what needs to be stated when solving a punnett square problem.

A
  • all possible genotypes
  • all possible phenotypes
  • offspring possibilities (percentage of geno/phenotypes occurring)
  • genotypic ratio (e.g. 1:2:1)
  • phenotypic ratio (e.g. 3:1)
30
Q

NON-MENDELIAN INHERITANCE PATTERNS
Describe what occurs in the following scenarios:
- incomplete dominance
- co-dominance

A

INCOMPLETE DOMINANCE
- when the genotype is heterozygous, neither gene is recessive to the other
- neither phenotype is expressed fully
- results in a ‘blend’ of the two traits
- e.g. R red + r white = Rr pink flower

CO-DOMINANCE
- when the genotype is heterozygous, there is no dominant allele
- results in both traits being expressed simultaneously (spots, speckles, patches)
- alleles are different letters (e.g. B + G) or with a common letter with subscript (e.g. C^B + C^G)

31
Q

Describe how there is co-dominance in human blood types:
- blood type phenotypes
- blood type genotypes
- how blood can be donated

A

PHENOTYPES
- type A (A antigens)
- type B (B antigens)
- type AB (A + B antigens)
- type O (no antigens, recessive)

GENOTYPES
A/B are codominant, but dominant over i recessive:
- A blood type: I^A, I^A, or I^A, i
- B blood type: I^B, I^B, or I^B, i
- AB blood type: I^A, I^B only
- O blood type: i, i only

DONATING BLOOD
- only give blood if it has antigens that are already in your blood type
- O: give to anyone, only receive O
- AB: give to AB, receive all blood types
- A/B: give to their own type and AB, receive own type and O

32
Q

State what can be found from a pedigree (4).

A
  • how traits are transmitted/inherited
  • predicted probability of having an affected child
  • if a trait is dom/recessive
  • if a trait is autosomal or sex-linked
33
Q

What characteristics of a pedigree chart display that the trait is X-linked recessive

A
  • sons would be affected if mother is affected (pass on recessive X chromosome)
  • affected daughter’s fathers must be affected (both daughters’ Xs must be recessive = father has recessive X)
34
Q

Chromosome

A

Genetic information
- contained in nucleus as strands
- before cell divides: DNA condenses into chromosome shape
- males = X + Y
- females = X + X

35
Q

Species

A

a group of living organisms that (most of time):
- are morphologically similar
- can produce fertile offspring with each other

36
Q

binomial

A

the system for naming organisms consisting of two terms
- 1st: Genus (capital)
- 2nd: species

37
Q

evolution

A

the process of culminative change in the heritable characteristics of a population

38
Q

natural selection

A

the process in which organisms that have better adaptions will flourish
- organisms with beneficial traits suited to the enviro will survive, produce more offspring
- over time, the beneficial traits become more frequent
- by this process, species evolve to better suit their environment

39
Q

State the 4 sections that need to be addressed when answering natural selection questions.

A
  1. there is genetic variation due to random mutation from sexual reproduction, leading to different traits (resulting in… state specific trait)
  2. not all organisms will reach maturity due to the selective pressure (state specific one)
  3. survival of the fittest: the organisms with the specific advantage (state) are able to… (state how trait gives advantage), and therefore survive at higher rates compared to organisms w/o it, and go on to reproduce more, passing the trait on to their offspring
  4. over time, the allele gene pool will change and the specific advantageous trait (state) will become more common
40
Q

allele frequency

A

how common/the frequency at which specific alleles occur within a population
- changed by evolution/speciation/genetic drift

41
Q

fertile

A

an organism that can produce offspring

42
Q

morphologically similar

A

organisms that LOOK the same/have similar physical features

43
Q

divergent vs convergent evolution

A
  • Divergent: species diverge from a common ancestor and therefore have similar characteristics
  • Convergent: species with different ancestors develop similar traits
44
Q

speciation

A
  • new species evolve when populations become isolated
  • they evolve independently (due to random mutation and natural selection)
45
Q

allopatric isolation

A

populations that are geographically isolated by a physical barrier
- have specific adaptations to a specific enviro
- over time, speciation occurs

46
Q

sympatric isolation
- different types (4)

A

populations that are isolated in another way:
- Temporal: species breed at different times of the day/year (e.g. nocturnal)
- Behavioural: unique mating behaviors identifies a species and only attracts same species
- Mechanical: unique reproductive organs/methods prevent reproduction between populations
- Gametic: sperm cannot fertilise another species’ eggs (occurs in marine enviros)

47
Q

post-reproductive barriers

A

The zygote develops, but:
- offspring are infertile and cannot go on to reproduce
- embryo cannot develop, dies before birth
- embryo is incompatible with the mother

48
Q

hybridisation

A

the breeding of two similar but different species
- often infertile
- often weaker/less fit

49
Q

rate of speciation

A

a debate about whether speciation is:
- gradualism: occurs gradually
- punctuated equilibrium: occurs rapidly

50
Q

GENETIC DRIFT
- what is it?
- what is it caused by
- what does it do to a pop?
- more prominent in…
- describe the two ways in which it occurs

A

GENETIC DRIFT
- evolution that is caused by random/chance events
- not natural selection
- an event removes part of a pop: the new pop has a reduced + different gene pool, different to the source pop
- now diff alleles have a higher frequency of occurring, resulting in evolution over time
- speciation will likely occur if the population is geographically isolated
- results in more prominent change in small pop.s, due to small gene pool with less variation

FOUNDER EFFECT
- random event leads to the colonisation of a new area by a limited no. of individuals from a source pop

BOTTLENECK (DISASTER)
- random disaster leads to a large reduction in pop. size
- individuals survive by chance, not by having an advantageous trait

51
Q

Describe the pros (4) and cons (4) of mitosis (asexual reproduction).

A

PROS
- time and energy efficient (allow rapid reproduction)
- advantageous traits guaranteed to be passed down
- can occur in wide variety of enviro conditions
- 1 organism can establish a population

CONS
- limited genetic diversity (clones, only source of variation is random mutation)
- negative traits guaranteed to be passed down
- change in enviro conditions can eliminate an entire pop (if no resistance)
- replication of defective cells can become uncontrolled (cancer)

52
Q

Describe the pros (3) and cons (3) of meiosis (sexual reproduction).

A

PROS
- high genetic variability (from crossing over/ind. assortment)
- more adapted + protected from disease, defects and enviro change
- negative genetic traits are not guaranteed to be passed down

CONS
- not time or energy efficient (embryo development takes time = slow pop growth)
- requires 2x gametes from 2x different organisms
- requires favourable/safe conditions

53
Q

types of disease
- non infectious
- infectious

A

non infectious
- cannot be transmissible (except genetically)
- not caused by a pathogen
- cause by: genetics, lifestyle, enviro, substance abuse
- e.g cancers, genetic disorders, diabetes, mental illness

infectious
- transmissible/communicable
- caused by the infection of a pathogen into blood/body fluids/cells

54
Q

pathogen

A

disease causing agent

55
Q

modes of transmission
- contact
- non contact

A

CONTACT
- pathogen is on organism/object (carrier)
- touched by organism directly
- Direct: physical contact between two organisms (touching, biting, intercourse, kissing), contact/exchange of body fluids
- Indirect: organism comes into contact w inanimate object (fomite) that pathogen is deposited on
- Droplets: organism comes into contact w infected body fluid within 1m of source, then inhaled

NON CONTACT
- Airborne: transmission via tiny droplets (aerosols), over 1m from source (e.g. flu, covid)
- Vehicle: food/water is contaminated (e.g. water borne viruses, food poisoning)
- Vector: another organism (animal/plant) is infected and carries pathogen

56
Q

State the types of pathogen, what each is/how they work, and some examples. (6)

A

PRIONS
- altered/abnormal protein made in cell
- cells fill with them and burst, spreading to other cells and continuing production
- break down brain tissue
- no known treatments

VIRUSES
- ultramicroscopic
- piece of RNA/DNA wrapped in a capsid (protein coat)
- reproduce inside a host cell
- cell bursts, spreading to other cells
- treatments: antiviral reduces severity, vaccine reduces infection likelihood and severity

BACTERIA
- prokary cells (some pathogenic)
- reproduce by binary fission (fast asexual reprod)
- if harmful, can: destroy cells/tissues due to enzymes, produce waste toxins, exaggerate immune response to foreign cells
- treatment: antibiotics stop cells functioning

PROTOSOAN
- single celled parasite (some pathogenic)
- e.g. malaria

FUNGI
- eukary organisms (some pathogenic)
- made of network of fungi spores, spread easily
- thrive in moist dark conditions

MACROPARASITES
- multicellular organisms
- dependent on host for life cycle
- endo (live in host, e.g. worms, flukes) ecto (live on host, e.g. lice, ticks, fleas)

57
Q

State the purpose for each of the 3 lines of defence.

A
  • body’s immune system - defence against disease/pathogens, malfunctioning cells, foreign particles

First line
- prevents entry
- innate
- non-specific
- mechanical/chemical barriers

Second line
- after pathogen entry (body fluids/tissue/cells)
- innate
- non-specific

Third line
- creates defence to a pathogen that body previously exposed to
- adaptive (not innate)
- specific

58
Q

FIRST LINE OF DEFENCE
- mechanical
- physical
- chemical
- biological

A

Mechanical (‘structural’)
- physically stop pathogen from entering body
- external: skin, hair (eyelashes, genitals, ears, nose)
- internal: mucous membranes (produce mucous that lines body tracts/openings, traps pathogens, cilia maneuver mucous up and out)

Physical
- attempt to expel pathogen from body systems
- coughing, sneezing, vomiting, urination, diarrhoea

Chemical
- acids/enzymes make conditions unfavourable
- tears, saliva, mucous, sweat

Biological
- good bacteria outcompete pathogens for space, and produce toxins that kill them

59
Q

SECOND LINE OF DEFENCE
- blood lymph systems (functions of both)
- WBCs (2 types, which is 2nd line, phagocytosis?)
- inflammatory response (4 steps)
- fever
- chemicals (cytokines, complement proteins)
- NK cells
- clotting

A

BLOOD/LYMPH SYSTEMS
- responsible as transportation network for 2nd/3rd line of defence
- Blood: produces WBCs and transports to infection site
- Lymph: a network of lymph capillaries/vessels, interconnected w blood capillaries, filters out lymph (blood plasma), transports to lymph nodes + tissue around body, pathogens/damaged cells filtered out of body

WBCs
1. Phagocytes (2nd line)
- engulf + digest pathogens
- Phagocytosis: phagocytes move from blood to infection site, devour foreign materials by endocytosis
- Neutrophils: first on site, large numbers, die after phagocytosis
- Macrophages: made in bone marrow, mature + stay in lymph system

  1. Lymphocytes
    - B + T lymphocytes (3rd line)
    - NK cells (2nd line)

INFLAMMATORY RESPONSE
- body’s reaction when cells/tissue are damaged
1. Mast cells (in connective tissue) release histamines when damaged, which signal:
2. Vasodilation (increase blood flow) and increased permeability (increase fluid flow to site)
3. Phagocytes (neutrophils/macrophages) to area to engulf pathogens
4. = inflammation (area becomes swollen, hot, red)

FEVER
- triggered if pathogens enter body + cause lrg scale infection
Causes:
- increased body repair (increased metabolism)
- reduction of microbial multiplication (fever reduces iron lvls, bacteria need for reprod)
- slowing of pathogen replication (temp over optimum)

CHEMICALS
Cytokines
- chemical messengers
- produced by macrophages
- intensity inflammatory response by signalling 2nd line defence mechanisms

Complement proteins
- produced by liver
- inactive until pathogen is detected
- Aid response: increase inflammation, signal phagocytes to area, break down bacteria cell walls
- bind to pathogen (mark for destruction)

NK CELLS
- lymphocyte
- patrol body tissue
- do not attack pathogens, only body’s own cells if: they are cancerous, invaded by a virus
- recognise body cell as malfunctioning: induce apoptosis (programmed cell death), kill by release of harmful substance

CLOTTING
- chemical signals cause a mesh of fibres to form over the site of damage
- traps RBCs
- platelets become sticky, creating clot
- prevents blood loss and entry of pathogens

60
Q

antigen vs antibody

A

Antigen
- specific proteins/polysacch.
- on outer surface of cells/viruses/released in bacteria toxins
- distinguish types of cell from another

Antibody
- large Y-shaped proteins
- produced by B-lymphocytes
- released into body fluids
- will only bind to specific antigen

61
Q

THIRD LINE OF DEFENCE
- humoural response
- cell-mediated response

A

HUMOURAL RESPONSE
- pathogen is in body fluids (not inside cells yet)
- involves production of antibodies

B-Lymphocytes
- produced and mature in bone marrow
- have specific antibodies, match to specific antigen
- when this occurs, the cell is activated: rapidly clones, producing:
- Effector/plasma cells: produce specific antibodies
- B-memory cells: remember how to make the specific antibodies if reinfected

  • Antibodies work by: making pathogens insoluble (cannot infect cells), clump together (easier phagocytosis removal), neutralise viruses (prevent attachment to cells), etc

CELL-MEDIATED RESPONSE
- pathogen is in body cells
- no antibody production in this stage

T-Lymphocytes
- produced in bone marrow, mature in thymus gland
- receptors detect MHC I from body cells that are infected by a pathogen (display antigen fragments)
- T cell clones itself, forming:

Helper T
- must be activated by antigen presentation (pathogen fragments on MHC II on APCs)
- activated helper T controls rest of immune response
- clones itself into all types of T cell
- releases cytokines (triggers other immune cells e.g. phagocytes, B-lymphocytes, inflammation)
- check and balance (identifies + activates correct B lymphocyte = cloning and antibody production)

Cytotoxic T
- destroys cells identified as non-self (missing MHC I, or displaying pathogen antigen fragments on MHC I)
- binds w infected cell to kill (injects toxins, cause cell lysis)

Memory T
- stay in lymph tissue until cells reinfected 2nd time
- if exposed to antigen again, allow faster + more effective recognition

Supressor/regulatory T
- turn off immune response/antibody production
- once infection has been checked

62
Q

MHC markers

A

MHC I
- all body cells have on cell surface
- allow distinguishment between self/non-self cells to identify pathogens (absence/alteration of markers)
- allows pathogens to be marked for destruction

MHC II
- possessed by phagocytes after engulfing pathogen
- allows presentation of antigen fragments to lymphocytes (T/B cells)
- alerts body of foreign invader

63
Q

antigen presentation

A
  • APC (antigen presenting cells) present antigen fragments on MHC II
  • activate T+B lymphocytes
  • if body’s own cells: present pathogen’s antigens on MHC I, signals they are a threat + must be destroyed
64
Q

IMMUNITY
- what is it and how does it happen?
- active vs passive

A

Immunity
- organism must undergo adaptive response (3rd line, making of memory cells)
- must be exposed to pathogen’s antigens
- upon 2nd infection: memory cells activate, provoking stronger immune response
= immunity

Active
- body undergoes adaptive 3rd line (antibody/memory cell production)
- long lived immunity (can take time to form)
- Natural: exposed to antigens, infected, recovers
- Artificial: exposed to antigens via vaccine

Passive
- body does not undergo adaptive 3rd line (NO antibody/memory cell production)
- short lived immunity
- Natural: antibodies received by baby from mother (milk/placenta)
- Artificial: infected person injected w antibodies to help fight disease

65
Q

vaccines

A

contain:
- dead pathogens/antigens
- fragments of pathogens/antigens
- live but weakened pathogens
- mRNA (instructions to make pathogen’s antibodies)

Biology 315 (5 decks)

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