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Biology revision unit 2 Flashcards

KK1,KK2,KK3,KK4,KK5. Chromosomes, genotypes and phenotypes, patterns of inheritance, reproductive strategies, adaptations and diversity

1
Q

Draw DNA polymer structure

A

Phosphates = circle (first bit of structure)
Deoxyribose sugar =(hexagon in the middle)
Nitrogenous base = (last 2 hexagons)

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2
Q

What are the 4 nitrogenous bases found in DNA

A

Adenine
Guanine
Thymine
Cytosine

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3
Q

What bases bond together

A

Adenine and Thymine
Guanine and Cytosine

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4
Q

How is DNA packaged

A

Phosphates link together neighboring nucleotides together to form one-half of the double-stranded DNA molecule

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5
Q

How is DNA packaged into chromosomes

A

Double-stranded
Histones organize the DNA into coiled structures

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6
Q

Definition of Gene

A

A section of DNA that codes for a particular protein

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7
Q

Definition of Allele

A

Versions of a gene that code for variations of the phenotypic trait

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8
Q

Definition of Genome

A

All genetic material that is in a haploid set of chromosomes

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9
Q

Eg of how an allele is a different version of the same gene

A

E.g.: coat color in a rabbit. One allele may code for a grey colour and one may code for a black coat. Both for the same gene just a variation

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10
Q

Gene Locus definition

A

The position of a gene on a chromosome

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11
Q

Draw a eukaryotic chromosome and label its structure

A

Must have:
- Homologous Chromosomes
- Gene Locus
- Sister chromatids
- Centromere

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12
Q

3 features of Homologous chromosomes (what makes them homologous)

A

3 of the following:
-Length/Size
-Centromere position
-Same Genes at the same location
-Banding Pattern

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13
Q

What are the autosomal and sex chromosomes (what numbered pairs are what)

A

1-22nd pair are autosomal
23rd pair are sex chromosomes

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14
Q

Why do chromosomes come in homologous pairs

A

one is from the mother and one is from the father. Each gives one chromosome because of cell division. Makes sure the offspring have all the genes and the correct amount of DNA

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15
Q

How is a Karyotype created

A

Taken a photo of cells during the start of cell division when all the chromosomes are condensed
Steps are:
-Find a cell in metaphase
-Extract chromosomes
-take photograph
-Pair and sort

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16
Q

Relationship between chromosome size and number of genes

A

The bigger/larger the size of the chromosome the larger number of genes are found on them

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17
Q

What are 2 things you can find out from a Karyotype

A

Abnormalities in number of chromosomes
Sex of individual

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18
Q

What are the chromosomal abnormalities in a person with Down syndrome

A

Trisomy 21 (extra chromosome on 21)

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19
Q

What are the chromosomal abnormalities in a person with Klinefleders syndrome

A

XXY
(extra x)

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20
Q

What are the chromosomal abnormalities in a person with Turner syndrome

A

x
no y

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21
Q

Haploid cell and diploid cell difference

A

diploid cells contain two complete sets. Haploid organisms, on the other hand, only contain one complete chromosome set.

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22
Q

2 stages of Meiosis

A

Meiosis I and Meiosis II

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23
Q

Explain what occurs at each stage of meiosis I and II

A

Prophase 1= Chromosomes condense, crossing over occurs
Metaphase 1= Homologous chromosomes line up on cell equator
Anaphase 1=Homologous cells are seperated
Telephase 1=new nucelus are formed
Prophase 2=Chromosomes condense and nucleur envelope breaks down
Metaphase 2=Sister chromatids (chromsomes) line up on equator
Anaphase 2=Sister chromatids are sperated
Telephase 2=Nucleur envelope formed

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24
Q

define haploid

A

Haploid describes a cell that contains a single set of chromosomes

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25
define diploid
the presence of two complete sets of chromosomes in an organism's cells, with each parent contributing a chromosome to each pair.
26
Explain how genetic variation is created in chromosomes
Independant assortment- the alleles of two (or more) different genes get sorted into gametes independently of one another. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene. Therefore increases amount combinations of alleles the gamete can recieve and therefore increases genetic variation Crossing over-when genetic material is swapped between two chromosomes. (When homologous chromosomes come together to form tetrads, the arms of the chromatids can swap at random, creating many more possibilities for genetic variation of the gametes.)
27
Genotype definition
Genetic make up which determines the phenotype Combination of alleles determine for a gene
28
Phenotype definition
What is expressed, observable characteristics * Controlled by both the genotype and the environment
29
What are the factors that determine a phenotype
-Genotype -Epigenetics -enviroment
30
What is the combination of Alleles in a Heterozygous genotype
Aa (dominant and recessive)
31
What is the combination of Alleles in a homozygous genotype
aa or AA (both dominant alleles or both recessive alleles)
32
How will a genotype with complete dominance (dominant or recessive) affect the expression of the phenotype
1 Dominant allele present means that the dominant allele will be expressed 2 recessive alleles required for the recessive phenotype to be shown
33
How will a genotype with co-dominance affect the expression of the phenotype
AA = dominant trait Aa = both traits expressed aa-recessive trait (not really recessive but)
34
How will a genotype with incomplete dominance affect the expression of the phenotype
AA=dominant Aa=intermediate of both traits aa= recessive
35
compare co domiance and incomplete dominance
co-dominance = both traits are expressed fully incomplete = an intermediate of the traits is expressed What they have in common = both express some version of both alleles
36
define epigenetics
the study of changes in an organism (modification of gene expression)
37
What does an epigenetic factor do
Change how DNA is packaged
38
What is an example of a epigenetic factor to do with lifestyle
diet, obesity, physical activity, tobacco smoking, alcohol consumption, environmental pollutants, psychological stress
39
What is methylation
the addition of a methyl group to a cytosine base
40
what does methylation do
stops the gene from being transcribed (stops transcription proteins from binding)
41
What does a shaded square stand for in a pedigree
an affected male
42
What does a shaded circle stand for in a pedigree
an affected female
43
What does a unshaded square stand for in a pedigree
an unaffected male
44
What does a unshaded circle stand for in a pedigree
an unaffected female
45
what does the line between a unrelated male and female mean in a pedigree
marriage line
46
what does a half shaded circle or square mean in a pedigree
a carrier
47
Brown eyes are a dominant eye-color allele and blue eyes are recessive. A brown-eyed woman whose father had blue eyes and whose mother had brown eyes marries a brown-eyed man whose parents are also brown-eyed. They have a son who is blue-eyed. Draw a pedigree (info above) showing all four grandparents, the two parents, and the son. Indicate each individuals possible genotypes.
work it out
48
define the law of segregation
The Law of Segregation states that alleles segregate randomly into gametes: When gametes are formed, each allele of one parent segregates randomly into the gametes, such that half of the parent's gametes carry each allele
49
What is the genotypic and phenotypic ratio of a monohybrid cross between 2 heterozygous individuals(trait shows complete dominance)
genotypic = 1:2:1 phenotypic =3:1
50
What is the genotypic and phenotypic ratio of a monohybrid cross between a heterozygous individual and a homozygous dominant(trait shows complete dominance)
Genotypic = 1:1 Phenotypic = all dominant
51
What is the genotypic and phenotypic ratio of a monohybrid cross between a heterozygous individual and a homozygous recessive(trait shows complete dominance)
genotypic=1:1 phenotypic = 1:1
52
What is the genotypic and phenotypic ratio of a monohybrid cross between a homozygous dominant individual and a homozygous recessive(trait shows complete dominance)
Genotypic= all heterozygous phenotypic =.all dominant
53
What is the genotypic and phenotypic ratio of a monohybrid cross between 2 heterozygous individuals(trait shows incomplete dominance)
genotypic = 1:2:1 phenotypic = 1:2:1
54
what is the genotypic and phenotypic ratio of a monohybrid cross between a carrier mother of a x linked recessive trait and a unaffected father
genotypic = 1:1:1:1(Dom female, carrier female, dom male, affected male) phenotypic =2:1:1
55
what is the genotypic and phenotypic ratio of a monohybrid cross between a unaffected mother of a x linked recessive trait and a affected father
genotypic =1:1 phenotypic = 1:1
56
what is the genotypic and phenotypic ratio of a monohybrid cross between a unaffected mother of a x linked dominant trait and an affected father
genotypic = 1:1 Phenotypic =1:1
57
Draw a monohybrid cross between 2 heterozygous individuals. The recessive genotype is lethal. What is the phenotypic and genotypic ratio
genotypic ratio = 2:1 phenotypic ratio = all domiant
58
Draw a monohybrid cross between 2 heterozygous individuals. having 2 of the dominant alleles is lethal. What is the phenotypic and genotypic ratio
g=2:1 p= 2:1
59
what is a monohybrid test cross
a cross between an individual showing the dominant allele and an individual showing the recessive allele
60
what is the purpose of a monohybrid test cross
to find out the genotype of the individual showing the dominant phenotype
61
Explain how two genes will independently assort or be linked over generations.
Genes on separate chromosomes assort independently because of the random orientation of homologous chromosome pairs during meiosis. Genes on the same chromosome will independently assort together meaning they are inherited together. Can only be separated by crossing over but it is rare.
62
How is a dihybrid cross different from a monohybrid cross
A dihybrid cross looks at the probability of inheritance of 2 genes not just one unlike a monohybrid cross
63
determine the possible gamete combinations of an individual with the genotype AABb
AB Ab AB Ab
64
determine the possible gamete combinations of an individual with the genotype AaBb
AB Ab aB ab
65
determine the possible gamete combinations of an individual with the genotype aaBb
aB ab aB ab
66
what is the phenotypic ratio in a dihybrid cross with 2 heterozygous individuals for both traits
9:3:3:1
67
If 2 genes are linked. what is the genotypic ratio/phenotypic
usually around 49:1:1:49
68
What are the genotypes of the offspring called when linked genes are separated due to crossing over
recombinants
69
What does the word parthenogenesis mean
Virgin birth
70
what is pathogenesis
Reproduction without fertilisation. Egg is produced by mitosis.
71
What is facultative pathogenesis
pathogenesis used when required i.e. when there is a lack of males.
72
What is Obligate pathogenesis
Are an all female population (used always)
73
What is budding
A small part of the parent body separates from the rest and develops into a new individual, which is smaller than the parent. Note: This new individual may remain attached as part of the colony, or the bud may constrict at its point of attachment and be released as an independent organism.
74
What is fragmentation
The organism spontaneously divides into fragments. Each fragment develops into a mature, full grown individual identical to the original organism.
75
eg: of an organism that uses pathogenesis
Sharks, Komodo dragons
76
eg: of an organism that uses fragmentation
flatworms, starfish
77
eg: of an organism that uses budding
yeast, hydra
78
Name the stages of binary fission in prokaryotes
1. Replication: of circular DNA 2. Attachment: of the two circular DNA molecules to the poles of the plasma membrane. 3. Lengthening: of the cell 4. Division: into two cells by constriction across the middle of the cell.
79
Advantage of vegetative propagation
-helps preserve the characters of the plants through successive generations - they do not need to produce flowers,pollen, or seeds (processes with large energy costs).
79
Definition of vegetative propagation
The process by which new individuals arise without the production of seeds or spores
80
Name 4 types of vegetative propagation
Tubers, bulb, rhizomes, cuttings, grafting.
81
Advantages of asexual reproduction
-can reproduce quickly - no energy expended finding a mate - don't rely on other organisms -well suited to environment -able to colonise cleared areas quickly
82
Disadvantages of asexual reproduction
-Lack of genetic variation -pressure on availability of resources -if conditions change, entire population can be lost
83
Explain why some organisms use both sexual and asexual reproduction
So that they can reproduce in the way that most suits the current environmental conditions

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