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inheritance and variation Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

alleles?

A

varieties of a gene

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2
Q

crossing over of TT and tt

A

f1 progeny-all Tt

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3
Q

T

t

A

dominant

recessive

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4
Q

homozygous

A

same gene, eg: TT, tt

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5
Q

heterozygous

A

different, eg: Tt

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6
Q

monohybrid cross

A

A monohybrid cross is a genetic mix between two individuals who have homozygous genotypes

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7
Q

segregation

A

separation of alleles of the parental pair from each other and only one allele is transmitted to a gamete

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8
Q

test cross

A

it’s an experiment in which the dominant phenotype with an unknown genotype is crossed with a recessive parent

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9
Q

LAWS OF INHERITANCE

A
  1. law of dominance

2. law of segregation

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10
Q

law of dominance

A

Mendel’s law of dominance states that in a heterozygote, one trait will conceal the presence of another trait for the same characteristic

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11
Q

law of segregation

A

refer to def. of segregation

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12
Q

incomplete dominance

A

when the dominant trait is not completely expressed when the recessive trait (allele) is around,eg: snapdragon flower

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13
Q

codominance

A

were both the traits or alleles are expressed in the f1 progeny eg; determine ABO blood grouping in humans

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14
Q

ABO controlled by -

A

GENE I

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15
Q

multiple alleles

A

Multiple alleles exist in a population when there are many variations of a gene present

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16
Q

explain starch synthesis on the basis of gene

A
  • its controlled by one gene , it has 2 alleles B and b
  • its properly synthesized by BB homo zygotes and produce larger amounts
  • bb homozygotes have lesser efficiency in starch synthesis
  • in Bb seeds starch is produced in intermediate amounts
  • BB seed are round , bb are wrinkled
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17
Q

dihybrid cross

A

a cross between 2 pairs of alleles ,eg:HhSs and hhss

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18
Q

law of independent assortment

A

it states that the segregation of one pair of character is independent of the other pair of character ( alleles are not linked )

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19
Q

why was mendels work not excepted?

A

due to

  • lack of communication
  • non blending inheritance
  • use of mathematics to explain biology
  • no physical proof of the existence of genes and chromosomes
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20
Q

who are the 2 scientists who rediscovered mendele’s work

A

de vries , correns and von teschermak

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21
Q

boveri - sutton theory ?

A

its now called the chromosomal theory of inheritance , it sates that individual genes are found at specific locations on the chromosome , the pattern of behaviour of chromosomes during meiosis explains the mendel
laws as to why , how genes are created

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22
Q

expalin the work of thomas hunt morgan

A

he worked with tiny fruit flies , drosophila melanogaster
they were suitable because they could be grown in a synthetic medium in a lab , the male and the female flies could be differentiated , they complete their life cycle in 2 weeks , can produce large no. pf progeny flies

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23
Q

polygenic traits

A

when many genes code for one trait , eg; skin colour , height

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24
Q

pleiotropic gene

A

where one gene exhibits multiple phenotypic expressions

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25
Q

disease phenylketonuria?

A

it occurs in humans which is caused by the mutation in the gene which codes for the enzyme phenyl alanine hydroxylase. this manifests itself through phenotypic expressions which result in mental retardations , hair loss and pale skin

26
Q

autosome

A

An autosome is any chromosome that is not a sex chromosome

27
Q

number of chromosomes in human male and female

A

In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females

28
Q

X0 type of sex determination

A

Males only have one X chromosome (X0), while females have two (XX). O signifies the lack of a second X. Maternal gametes always contain an X chromosome, so the sex of the animals’ offspring depends on whether a sex chromosome is present in the male gamete.

29
Q

example of xo type

A

grasshoppers

30
Q

Do you think the number of chromosomes in male and female are equal in grasshopper?

A

NO

31
Q

male heterogamety

A

The production by males of some species, such as humans and Drosophila, grasshopper, of two types of gametes that differ in their sex chromosome content.

32
Q

female heterogamety

A

2 different types of gametes in terms of sex chromosome are produced by females like in birds

33
Q

sex determination in honey bee

A

haploid diploid system

34
Q

female honey bee-

male -

A

develop from a fertilized egg

develop from an unfertilized egg by parthenogenesis

35
Q

parthenogenesis

A

is a natural form of asexual reproduction in which the growth and development of embryos occur without fertilization by sperm.

36
Q

female honey bee-

male …-

A

diplod(36)

haploid(16)

37
Q

mutation

A

it’s a phenomenon that results in the alteration of DNA sequence which results in the change of phenotype and genotype of the organism

38
Q

how mutation occurs?

A

by loss or gain of DNA result in change in chromosomes, exposure to ionizing radiation, exposure to chemicals called mutagens

39
Q

point mutation?

A

when there’s is a change in a single base pair of DNA
eg; sickle cell anemia
deletion and insertion of base-pair result in frame-shift mutation

40
Q

pedigree analysis

A

By analyzing a pedigree, we can determine genotypes, identify phenotypes, and predict how a trait will be passed on in the future. The information from a pedigree makes it possible to determine how certain alleles are inherited: whether they are dominant, recessive, autosomal, or sex-linked.

41
Q

Mendelian disorders

A

they are determined by a mutation in a single gene

42
Q

Mendelian disorders examples

A 
Sickle cell anaemia.
Cystic fibrosis.
Thalassemia.
Phenylketonuria.
Colour blindness.
Haemophilia.
43
Q

Colour blindness.

A

it is a sex-linked recessive disorder, carried on the x chromosome, due to defect in either green or red cone of the eye resulting in failure to differentiate between red and green colour which is due to mutation of certain genes in the X chromosome

44
Q

haemophilia

A

sex-linked recessive trait, here a single protein that is a part of the cascade of proteins which is involved in the clotting factors is affected so a single cut will result in non-stop bleeding

45
Q

sickle cell anaemia

A

it is an autosome linked recessive trait
it is caused when both the parents are carriers for the gene, it is controlled by the allele HBA and HBS, the individual should be homozygous(HBS HBS)to show the disease

46
Q

what is HBA and HBS

A

HBA - Normal haemoglobin

HBS- sickle haemoglobin

47
Q

how sickle cell anaemia is caused

A

it is caused by the substitution of glutamic acid by valine at the 6th position of the beta-globin chain

48
Q

phenylketonuria

A

autosomal recessive trait, here the person lacks the enzyme that coverts phenylalanine into tyrosine as a result phenylalanine levels increases and the tyrosine decreases as result phenylalanine is converted to phenyl pyruvic acid. accumulations of these in the brain result in mental retardation

49
Q

thalassemia

A

autosomal recessive trait

2 types depending upon which chain of the haemoglobin is affected (alpha and beta-globin)

50
Q

beta-thalassemia

A

where there’s a deficiency in the production of the beta-globin chains of the haemoglobin, here it is controlled by a single gene HBB on the 11 chromosome of each parent and occurs due to mutation of one or both the genes

51
Q

alpha thalassemia

A

where there’s a deficiency in the production of the alpha-globin chains of the haemoglobin, it is controlled by 2 linked genes HBA1 and HBA2 on chromosome 16
of the 2 parents and it’s observed due to mutation or deletion of one or more of the 4 genes

52
Q

chromosomal disorders

A

it is caused by the excess or abnormal or absence of arrangement of one or more chromosomes

53
Q

aneuploidy

A

causes when there’s a failure in the segregation of the chromatids during cell division which results in excess or loss of chromosomes

54
Q

polyploidy

A

causes when there’s a failure in the cytokinesis after telp\ophase stage during cell division which results in an increase in a whole set of chromosomes in an organism which often occurs in plants

55
Q

trisomy

A

gain of an additional copy of a chromosome

56
Q

monosomy

A

loss of any one pair of chromosome

57
Q

down syndrome

A

down syndrome is a condition in which a child is born with an extra copy of their 21st chromosome — hence its other name, trisomy 21. This causes physical and mental developmental delays and disabilities.

58
Q

turners syndrome

A

absence of one of the X chromosome, 45 with X0

results in lack of secondary sexual characters

59
Q

klinefelters syndrome

A

Klinefelter syndrome is a genetic condition affecting males due to a presence of an additional copy of chromosome resulting in karyotype 47

60
Q

symptoms of Klinefelter’s syndrome

A

they have overall masculine characters but also some feminine development like breasts

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