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Biology 1 & 2 > how is inheritance explained? > Flashcards

how is inheritance explained? Flashcards

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1
Q

deoxyribonucleic acid definition (DNA)

A

a double stranded nucleic acid chain made-up of nucleotides. DNA carries the instructions for proteins which are required for cell and organism survival.

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2
Q

nucleic acid definition

A

the class of macromolecules that includes DNA and RNA. All nucleic acids are polymers made out of nucleotide monomers.

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3
Q

nucleotide definition

A

the monomer unit of nucleic acids. Made-up of a nitrogen-containing base, a sugar molecule (ribose in RNA and deoxyribose in DNA) and a phosphate group.

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4
Q

gene definition

A

a section of DNA that carries the code to make a protein. Genes are what form the basis of inheritance, and can be found at specific locations on chromosomes (gene loci)

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5
Q

genome definition

A

the complete haploid set of DNA/ chromosomes contained within an organism, including all of its genes. A copy of the entire genome is contained in all cells within the body that have a nucleus.

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6
Q

allele definition

A

an alternative form of a gene. Humans typically have two alleles - one from each parent which are found at the same gene locus on corresponding chromosomes.

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7
Q

histone protein definition

A

highly basic proteins that associate with DNA inside the nucleus and help it condense into a chromosome allowing it to fit inside the nucleus.

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8
Q

chromosome definition

A

the structure made of protein and nucleic acids that carries genetic information.

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9
Q

somatic cell definition

A

any cell that is not a reproductive cell. Somatic cells are diploid (2n), meaning they contain two sets of chromosomes - one inherited from each parent.

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10
Q

chromatid definition

A

one half of a replicated chromosome. Prior to cell division, chromosomes are duplicated and two copies join together at their centromere (joined chromatids are known as sister chromatids)

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11
Q

homologous chromosome definition

A

a pair of chromosomes of similar length and shape, gene position, and centromere location. One of the pair is inherited from the mother (maternal chromosome) and the other from the father (paternal chromosome)

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12
Q

homologue definition

A

a homologous chromosome

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13
Q

karyotype definition

A

a visual representation of individuals entire genome organized into homologous pairs

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14
Q

autosome definition

A

any chromosome (1-22) in humans that is not a sex chromosome

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15
Q

sex chromosome definition

A

a chromosome responsible for determining the biological sex of an organisms. In humans, sex chromosomes can be either X or Y chromosomes

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16
Q

aneuploidy definition

A

when a cell or organism varies in the usual number of chromosomes in its genome by the addition or loss of a chromosome.

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17
Q

monosomy definition

A

when an organism has one missing chromosome (2n-1)

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18
Q

trisomy definition

A

when an organism has one extra chromosome (2n+1)

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19
Q

tetrasomy definition

A

when an organism has two extra chromosomes (2n+2)

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20
Q

polyploidy definition

A

when an organism contains additional sets of chromosomes in its genome. In humans, this would mean that rather than being diploid (2n=46), the individual would be 3n = 72 or more.

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21
Q

recall 5 chromosomal abnormalities/disorders

A
  1. Down syndrome
  2. Klienfelters syndrome
  3. Turners syndrome
  4. Cri-du-chat syndrome
  5. Patau syndrome
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22
Q

define down syndrome

A

trisomy of chromosome 21; distinct eye shape, shorter stature, intellectual disability

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23
Q

define kleinfelters syndrome

A

XXY (extra X chromosome in a male); tall, less muscular than average, broad hips, delayed puberty, less facial hair.

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24
Q

define turners syndrome

A

XO (one X chromosome in female is missing/partly deleted); short height, failure of ovaries to develop, heart defects.

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25
Q

define cri-du-chat

A

chromosome 5 deletion; mouth/facial malformations = distinct crying as an infant

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26
Q

define patau syndrome

A

trisomy 13; heart abnormalities, physical growth irregularities, extra fingers or toes, deformed feet, low birth weight.

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27
Q

meiosis definition

A

a specialised form of cell division used to produce gametes in sexually reproducing organisms

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28
Q

gametes definition

A

reproductive cells that arise from germline cells and contain half the genetic material (n) of a somatic cell. The gametes in animals are sperm and egg cells.

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29
Q

zygote definition

A

the diploid cell formed by the combination of two haploid gamete cells

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30
Q

germline cell definition

A

cells that are in the generation of gametes in eukaryotes

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31
Q

gonads definition

A

the organs that produce gametes from germline cells. In humans these are the testes (male) and ovaries (female)

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32
Q

summarise the difference between Meiosis 1 and Meiosis 2

A
  • Meiosis 1: seperates each homologous chromosome into two different cells
  • Meiosis 2: seperates each sister chromatid into four different cells.
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33
Q

metaphase plate definition

A

the equator of a dividing cell where chromosomes will line up during metaphase

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34
Q

microtubules definition

A

long tube like fibre proteins that from part of the cytoskeletonof a eukaryotic cell and help give the cell its structure. Microtubules are used for a variety of cell movements, including transport of a cells organelles and the movement of chromosomes during cell division.

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35
Q

cytokenesis definition

A

the division of the cytoplasm and formation of two daughter cells.

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36
Q

crossing over definition

A

the exchange of genetic material between non-sister chromatids during prophase 1 of meiosis, resulting in the combination of alleles in daughter cells. The chromosomes will ‘cross over’ at a point called the chiasma, each swapping part of their DNA with the other.

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37
Q

chiasma definition

A

the point/location of overlap between two non-sister chromatids

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38
Q

independant assortment definition

A

the random orientation of homologous chromosomes along the metaphase plate during metaphase 1. Each pair of homologues line up randomly, irrespective of the orientation of other homologous pairs.

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39
Q
A
40
Q
A
41
Q

what is this an example of?

A

crossing over

42
Q

what is this an example of?

A

independant assortment

43
Q
A
44
Q

diploid definition

A

having two sets (2n) of each chromosome, one from each parent

45
Q

homozygous definition

A

having identical alleles for the same gene on homologous chromosomes

46
Q

heterozygous definition

A

having different alleles for the same gene on homologous chromosomes

47
Q

dominant allele definition

A

the variant of a gene that masks the effect of a recessive alle of the same gene of a homologous chromosome

48
Q

recessive allele definition

A

the variant of a gene that is masked by a dominant alle on a homologous chromosome

49
Q

complete dominance definition

A

a pattern of dominance where only the dominant allele from the genotype of a heterozygous individual is expressed in a phenotype of that organism

50
Q

phenotype definition

A

the physical or biochemical characteristics of an organism that are a result of gene expression (or set of genes) and the environment

51
Q

carrier definition

A

an organism that has inherited a copy of a recessive allele for a genetic trait but does not display the trait due to it being masked by the presence of a dominant allele

52
Q

genotype definition

A

the genetic composition of an organism at one particular gene locus, as represented using letter symbols

53
Q

codominance definition

A

a pattern of dominance where both alleles from the genotype of a heterozygous individual are dominant and expressed in the phenotype of that organism independently

54
Q

incomplete dominance

A

a pattern of dominance where neither allele from the genotype of a heterozygous individual is dominant and expressed in an intermediate.

55
Q

sex linked genes definition

A

genes that are located on a sex chromosome

56
Q

x linked traits definition

A

a trait controlled by a gene that is located on the X chromosome

57
Q

y linked traits

A

a trait controlled by a gene that is located on the Y chromosome

58
Q

recall the key knowledge on the notation of a dominant genotype/phenotype

A

denoted by a capital letter, e.g A, this allele will always be expressed if it is present. It can ‘mask’ the recessive allele.

59
Q

recall the key knowledge on the notation of a recessive genotype/phenotype

A

denoted by a lowercase letter, e.g a, this allele is only seen if there are two copies of it, otherwise the dominant phenotype will hide it

60
Q

recall the key knowledge on the notation oh a homozygous individual

A

two of the same, e.g homozygous dominant = AA vs. homozygous recessive = aa

61
Q

recall the key knowledge on the notation of a heterozygous individual

A

one of each, e.g Aa (can be a ‘carrier)

62
Q

recall the key knowledge on the notation of codominance/ incomplete dominance

A

e.g A^aA^b or C^RC^W, both dominant genes with different allele types

63
Q

environment definition

A

the conditions and resources external to an organism with which that organism typically interacts

64
Q

proportionate heritability definition

A

the amount of phenotypic variance that can be explained by genes in a given population

65
Q

epigenetics definition

A

changes to an organisms phenotype resulting from modification to gene expression
* the study of how cells control gene activity without changing the DNA sequence

66
Q

gene expression definition

A

the process of reading the information stored within a gene to create a functional product, typically a protein

67
Q

a gene is expressed when the protein it carries the instructions for is built by ca cell, this occurs through…

A

transcription and translation

68
Q

transcription definition

A

the process whereby a sequence of DNA is used to produce a complementary sequency of mRNA

69
Q

translation definition

A

the process whereby an mRNA sequence is used to produce a protein

70
Q

explain what epigenetic changes are

A

epigenetic changes alter the process of transcription. They are caused by molecules that increase or decrease the amount of transcription of a particular gene and therefore alter the amount of protein that is produced. In this way, epigenetics can regulate the expression of specific proteins, which is important for a number of different areas of growth and development of organisms.

71
Q

recall the two types of epigenetic changes…

A
  1. DNA methylation
  2. Histone modification
72
Q

DNA methylation definition

A

the process by which methyl (-CH₃) groups are added to particular nucleotides in a DNA segment so as to modify the expression of a gene

73
Q

DNA demethylation definition

A

refers to the removal of methyl groups from a DNA sequence, and typically leads to a gene being expressed

74
Q

Histone modification definition

A

occurs when histone modifying enzymes known as histone methyl transferase (HMT) join methyl groups to histone tails and modify how tightly a DNA molecule is wrapped around it. If the DNA is condensed tighter around the histone, it makes it more difficult for the genes to be transcribed and less likely to be expressed. Alternatively, if the DNA becomes less tightly packed, the genes will be easier to transcribe and more likely to be expressed.

75
Q

epigenetics are…

A

somatically heritable

76
Q

somatically heritable definition

A

genetic traits or alterations to a cell which are inherited by daughter cells during the course of regular mitotic division

77
Q

monohybrid cross definition

A

a genetic cross performed to observe the inheritance of alleles and phenotypes for a single gene

78
Q

punnett square definition

A

a square diagram used to predict the genotypes of offspring

79
Q

recall the seven steps for how to complete an autosomal complete punnett square

A
  1. Assign letters to each allele
  2. draw a 2x2 grid
  3. write each of the fathers alleles above the column
  4. write each of the mothers alleles beside one row
  5. complete the cross to determine the potential offspring genotypes. Ensure you write the dominant allele first in the heterozygous offspring
  6. Calculate the fractional proportions of each potential genotypes by determining the frequency of each genotypes then dividing it by the total number of squares (4). Multiple this fraction by 100 to determine the percentage of each genotype
  7. Determine the phenotype of each offspring by looking at the genotypes. To calculate the fractional proportions of each phenotype, determine the frequency of each phenotype then divide it by the total number of squares. Multiply this fraction by 100 to determine the percentage of each phenotype.
80
Q

test cross definition

A

when an individual expressing the dominant phenotype but with an unknown genotype is crossed with a homozygous recessive individual. The results indicate whether the individual with the dominant phenotype is homozygous dominant or heterozygous

81
Q

dihybrid cross definition

A

a genetic cross used to observe the inheritance of alleles and phenotypes for two genes

82
Q

unlinked genes definition

A

genes located on different chromosomes, or far apart on the same chromosome. Unlinked genes have less chance of being inherited together

83
Q

to determine the different gametes produced by an individual (done prior to completing a dihybrid punnett square) during meiosis, the _____ is used

A

FOIL method
F - First alleles
O - outside alleles
I - inside alleles
L - last alleles

84
Q

recall the seven steps of how to complete a dihybrid punnett square

A
  1. Assign letters to each allele
  2. Draw a 4x4 grid
  3. Write each of the fathers allele combinations above one column
  4. Write each of the mothers allele combinations beside on row
  5. Complete the cross to determine the potential offspring genotypes. Ensure you write the dominant allele first in heterozygous offspring
  6. Calculate the fractional proportions of each potential genotype by determining the frequency of each genotype then dividing it by the total number of squares. Multiply this fraction by 100 to determine the percentage of each genotype
  7. Determine the phenotype of each offspring by looking at the genotypes. To calculate the fractional proportions of each phenotype, determine the frequency of each phenotype then divide it by the total number of squares. Multiply this fraction by 100 to determine the percentage of each phenotype
85
Q

explain the knowledge of the relation between linked genes and crossing over

A

genes that are located more closely together on the same chromosome are known as linked genes. This means that during meiosis, because they are on the same chromosome, they are inherited together and are not separated during independant assortment. Linked genes, however, can occassionally be seperated through crossing over

86
Q

the chances of crossing over occurring are calculated by using…

A

map units. One map unit equates to a one percent chance of crossing over and the offspring containing a recombinant chromosome.

87
Q

map units definition

A

a measure of the distance between two genes on the same chromatid. Genes that are closer together are more likely to be linked genes.

88
Q

recombinant chromosome definition

A

a chromosome which is not identical to one of the homologous chromosomes in a diploid cell

89
Q

parental chromosome definition

A

a chromosome which contains the same combination of alleles as one of the parents chromosomes

90
Q

recall the seven steps on how to complete a linked dihybrid cross punnett square

A
  1. Assign letters to each allele
  2. Determine each of the possible alleles in each gamete for the parents and the chances of this happening, be sure to account for crossing over
  3. Draw a 1x4 grid
  4. write each of the non-homozygous recessive individuals allele combinations above one column and note which combinations are parental and which are recombinant
  5. write the homozygous recessive alleles next to the one row
  6. Complete the cross to determine the potential offspring genotypes. Be sure to use the correct conventions for writing genotypes for linked genes
  7. Write the percentage chance of this genotype occurring below each square
91
Q
A
92
Q

pedigree chart definition

A

a diagram showing the expression of a trait over multiple generations

93
Q

consanguineous breeding

A

breeding of two individuals that are closely related. Also known as inbreeding

94
Q

recall the knowledge related to identifying sex linked inheritance on pedigrees

A

it is important to note that sex-linked inheritance cannot be confirmed from a pedigree as it is possible for autosomal traits to produce pedigree charts that suggest sex-linked inheritance. So, instead of saying that sex-linked inheritance is confirmed, we say that sex-linked inheritance is more likely, as the chance of autosomal traits producing a pedigree chart that looks like sex-linked inheritance is very low.

95
Q
A
96
Q
A

Biology 1 & 2 (8 decks)

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