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Year 12 Biology > Chapter 9-11 > Flashcards

Chapter 9-11 Flashcards

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1
Q

Genetic counselling

A

provision of expert advice to prospective and actual parents about risks of occurrence or recurrence of inherited disorders

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2
Q

Genes determine our…

A

characteristics (phenotypes)

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3
Q

Genes are passed on from…

A

generation to generation

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4
Q

In our body we have how many sets of genes

A

double set, one from mother, one from father

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5
Q

Gamete

A

a haploid cell, that is able to unite with a gamete of the opposite sex to form a zygote

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6
Q

Haploid

A

a cell that has one copy of each specific chromosome

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7
Q

Cell cycle

A

is a set of events that occur cyclically that lead to the repeated replication of the eukaryotic cell

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8
Q

Cell cycle phases

A

G0 (resting), G1 (growth 1), S (synthesis), G2 (growth 2), M (mitosis/meiosis + cytokinesis)

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9
Q

What happens in S

A

DNA is duplicated as a result of the chromosomes duplicating

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10
Q

Important thing about cell cycle

A

only dividing cells are in the cell cycle, others are in G0

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11
Q

Meiosis

A

process of nuclear division that results in the production of new haploid cells

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12
Q

Mitosis

A

the process of nuclear division resulting in giving rise to two identical daughter cells.

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13
Q

Binary fission (where, results in, asexual or sexual)

A

where: prokaryotic cells

results in: exact copies of the cells (assuming there are no mutations)

is it asexual/sexual: asexual

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14
Q

Binary fission process

A
  • DNA replication occurs, the single circular chromosomes relocates into two circular chromosomes (Presumably plasmids and ribosomes replicate)
  • the twin chromosomes attach to opposite poles of the cell membrane
    the cell begins to elongate, dragging the chromosomes to opposite ends
  • the cell membrane and walk invaginated upon itself
  • the parent cell splits into two daughter cells as the cell membrane and wall separates the two new parent cells
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15
Q

Sexual cell reproduction involves

A

the fusion of gametes

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16
Q

Regulator genes

A

genes that produce proteins that control the action of other genes and these actions determine whether other genes are active (‘on’) or not (‘off’) and, if active, the rate at which their products are made.

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17
Q

Two ways that regulator gene proteins can act

A

DNA-binding proteins, signalling proteins

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18
Q

DNA-binding proteins

A

bind to regions of nuclear DNA near genes and directly switch these genes on or off (net positive charge)

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19
Q

Signalling proteins

A

bind to receptors on the membrane of cells in their target tissue and trigger a series of intercellular reactions that switch genes on or off

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20
Q

Human genome project

A

international project directed at the identification of the sequence of the more than three billion bases in the human genome.

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21
Q

Aim of human genome project

A

store the sequences in a data base to create a map of all the human genes.

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22
Q

Results caused by human genome project (5)

A

insights into diagnosis, treatment, prevention, human biology, evolution

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23
Q

The nature of genetic code

A

the genetic code consists of triplet base sequences, code is non-overlapping (e.g. 12 bases = only 4 triplets), said to be universal (virtually same in plants/animals/bacteria), is redundant (more than one triplet codes for same thing), information encoded in DNA is instructions to assemble polypeptides from amino acids, includes start and stop codons

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24
Q

Start codon

A

TAC

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25
Q

Number of stop codons

A

3

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26
Q

Stop codons

A

ATT, ATC, ACT

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27
Q

Genetic code

A

non-overlapping triplet code consisting of groups of three bases. The sequence of nucleotides, coded in triplets (codons) along the mRNA, which determines the sequence of amino acids in protein synthesis.

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28
Q

DNA sequence definition

A

relative order of base pairs, whether in a fragment of DNA, a gene, chromosome or an entire genome.

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29
Q

Gene

A

the fundamental physical and functional unit of heredity made of DNA. A gene is an ordered sequence of nucleotides located in a particular position on a particular chromosome that encodes a specific functional product

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30
Q

Gene expression

A

The process by which a gene’s coded information is converted into the structures present and operating in the cell. Expressed genes include those that are transcribed into mRNA and then translated into protein and those that are transcribed into RNA but not translated into protein (e.g., transfer and ribosomal RNAs).

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31
Q

Introns

A

The DNA base sequences interrupting the protein-coding sequences of a gene; these sequences are transcribed into RNA but are cut out of the message before it is translated into protein.

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32
Q

Exons

A

The protein-coding DNA sequences of a gene

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33
Q

Transcription

A

The synthesis of an RNA copy from a sequence of DNA (a gene); the first step in gene expression.

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34
Q

Translation

A

The process in which the genetic code carried by mRNA directs the synthesis of proteins from amino acids.

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35
Q

tRNA

A

A class of RNA having structures with triplet nucleotide sequences that are complementary to the triplet nucleotide coding sequences of mRNA.

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36
Q

Role of tRNA

A

to bond with amino acids and transfer them to the ribosomes, where proteins are assembled according to the genetic code carried by mRNA.

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37
Q

Promoter

A

a site on DNA to which RNA polymerase will bind and initiate transcription.

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38
Q

Polymerase (DNA/RNA)

A

Enzymes that catalyse the synthesis of nucleic acids on preexisting nucleic acid templates, assembling RNA from ribonucleotides or DNA from deoxyribonucleotides.

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39
Q

Primer

A

Short preexisting polynucleotide chain to which new deoxyribonucleotides can be added by DNA polymerase.

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40
Q

DNA replication

A

The use of existing DNA as a template for the synthesis of new DNA strands. In humans and other eukaryotes, replication occurs in the cell nucleus.

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41
Q

Karyotypes

A

graphic display of the complete set of chromosomes from a cell of a particular organism.

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42
Q

Ideogram

A

stylised representation of a haploid set of chromosomes arranged in order of decreasing size.

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43
Q

Autosomal chromosomes

A

homologous pairs that does not differ between the sexes

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44
Q

Autosomes can be distinguished by (3)

A

relative size, position on centromere, patterns of light and dark bands with special staining techniques

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45
Q

Sex chromosomes

A

determine the sex of the organism

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46
Q

Somatic cells (colloquial)

A

body cells

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47
Q

Mitosis

A

nuclear division of a somatic cell resulting in two identical daughter cells

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48
Q

Stages of Mitosis

A

(I) PMAT

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49
Q

Stages of Meiosis

A

(interphase i), prophase i, metaphase i, anaphase i, telophase i, cytokinesis i, prophase ii, metaphase ii, anaphase ii, telophase ii, cytokinesis ii

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50
Q

Interphase

A

G1, S, G2

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51
Q

Prophase

A

chromatin shortens and thickens into small compact chromosomes, spindle forms the centrosomes around the nucleus and approaches the nucleus, nuclear membrane breaks down

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52
Q

Metaphase

A

chromosomes align in a plane along the middle of the nucleus, the spindle attaches to the centromeres of the chromosome

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53
Q

Anaphase

A

spindle contracts, separating each double stranded chromosome into two single stranded chromosomes, and the single stranded chromosomes migrate to opposite poles of the cell, attached to the spindle

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54
Q

Telophase

A

the chromosomes uncoil and become less compact (decondense), two nuclear membranes reform

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55
Q

Cytokinesis

A

cytoplasm splits to identical daughter cells

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56
Q

When does crossing over occur

A

occurs in prophase i of meiosis

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57
Q

Aneuploidy

A

not the right number of chromosomes

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58
Q

Polyploidy

A

whole set of chromosomes fail to disjunct

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59
Q

Congenital disorders caused by…

A

mistakes in chromosome numbers and chromosomes abnormalities

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60
Q

Non-disjunction definition

A

when an error occurs in separation of chromosomes

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61
Q

Non-disjunction in 1st stage affects…

A

all 4 cells

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62
Q

Non-disjunction in 2nd stage affects…

A

2 only

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63
Q

Gonads

A

organs where gametes are formed

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64
Q

Germline cells

A

cells that give rise to gametes

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65
Q

How is zygote formed

A

nucleus of sperm fuses to nucleus of egg

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66
Q

What are the only cells to cross the genetic gap

A

gametes; all other cells die when the cell dies

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67
Q

Somatic cells definition

A

cells of the body that are diploid

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68
Q

How is DNA transmitted across generations

A

through gametes

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69
Q

Chromosomes

A

thread-like structures composed of DNA and protein

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70
Q

Chromosomes are only visible (under a microscope) during…

A

meiosis and mitosis

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71
Q

Chromosome map

A

drawing of a chromosome showing the gene loci

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72
Q

Structure of chromosome

A
  • has a centromere in the centre of the chromosomes
    - kinetochore
    - has a telomere at ends
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73
Q

The centromere has ….

A

constriction

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74
Q

Kinetochore (3)

A

surrounds the centromere, made of protein, forms the attachment points for spindle fibres necessary for movement

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75
Q

Telomere

A

DNA made up of thousands of repeats of sequences of base pairs
Telomere role - prevent chromosomes sticking together and they enable complete replication of chromosomes to occur.

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76
Q

Human telomere sequence

A

TTAGGG

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77
Q

Chromatids

A

two strands replicated chromosome which are joined together by a single centromere

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78
Q

Centromere

A

constricted part of the chromosome that contains the region where spindle fibres attach during meiosis and mitosis.

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79
Q

Loci/locus

A

the position of a gene on a chromosome

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80
Q

Linked genes are

A

on the same chromosome

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81
Q

Linkage groups are

A

refers to chromosomes, usually equal to haploid number of chromosomes.

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82
Q

Homologous chromosomes

A

a pair of chromosomes containing the same linear gene sequences, each derived from one parent. (but different alleles)

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83
Q

The larger the chromosome…

A

the more genes located on it

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84
Q

Chromosome mutations

A

include gross structural alterations of chromosomes, changes in numbers of chromosomes

85
Q

Gross structural alterations of chromosomes

A

includes translocation, inversions, duplication/deletion of sections of the chromosome

86
Q

Translocation

A

a section of one chromosome attaches to the end of another chromosome.

87
Q

Inversions

A

single chromosome undergoes breakage and a segment of the chromosome is reversed end to end (do not cause abnormalities in carriers as long as it is balanced with no extra/missing info)

88
Q

Changes in number or chromosomes is caused by

A

non-disjunction

89
Q

Non-disjunction causes…

A

aneuploidy and polyploidy organisms

90
Q

Aneuploidy

A

abnormal number of chromosomes

91
Q

Examples of aneuploidy

A

abnormal number of chromosomes

92
Q

Polyploidy

A

whole sets of chromosomes do not separate during meiosis

93
Q

Karyotypes

A

graphic display of the complete set of chromosomes from a cell of a particular organism.

94
Q

Autosomal chromosomes

A

homologous pairs that does not differ between the sexes

95
Q

Genome

A

the full set of genes of an individual

96
Q

Alleles

A

alternative forms/variants of a particular gene that controls one function

97
Q

Genotype

A

refers to both the double set of genetic instructions present in a diploid organism and to the genetic makeup of an organism at one particular gene locus

98
Q

Phenotype

A

expression of an organism’s genotype in its structural, biochemical and physiological characteristics

99
Q

Heterozygote

A

the presence of different alleles at one or more loci on homologous chromosomes

100
Q

Homozygote

A

an individual with both identical alleles (versions of a single gene) at one locus (position).

101
Q

Polygenes

A

many genes that work together to produce a trait.

102
Q

Polygenes cause… (type of variation)

A

continuous variation

103
Q

Continuous variation

A

results in characteristics which exhibit a continuos range of traits (phenotypes) across a population.

104
Q

Examples of continuous variation

A

height, skin colour, eye colour.

105
Q

Discontinuous variation

A

in a population occurs when members of a population can be grouped into a few discrete and non-overlapping classes with regard to expression of a trait

106
Q

Example of discontinuous variation

A

number of fingers

107
Q

Monomorphic population

A

all members have identical phenotypic trait

108
Q

Polymorphic population

A

members have several variants of particular trait

109
Q

Mutation

A

permanent change in the genetic material (or DNA sequence).

110
Q

Important to remember about mutation

A

spontaneous events

111
Q

Environment effect of genes can be either..

A

either internal or external

112
Q

Examples of environment effect on genes (2)

A

chemicals in external environment cause birth defects/alter appearance, absence of chemical in body - trait not expressed e.t.c.

113
Q

Test cross

A

a cross between an organism of interest (that exhibits the dominant trait) and an organism with a known recessive phenotype, in order to determine the genotype of a particular trait in the organism of interest, or if two genes are linked.

114
Q

Pedigree

A

a “family tree” that shows the frequency and occurrence of particular phenotypes (hence alleles) over many generations

115
Q

Symbol for male

A

square

116
Q

Symbol for female

A

circle

117
Q

Symbol for twins identical vs fraternal

A

identical has line through middle, fraternal has no line

118
Q

Identify if recessive

A

skips generation, both parents have it then all children have it

119
Q

Identify if sex-linked dominant pedigree

A

father = all daughters, if a son = mother must have

120
Q

Identify if sex-linked recessive

A

father has = all daughter, mother has = all sons

121
Q

Sex-linked trait

A

an allele (gene) that is found on the sex chromosomes (usually X)

122
Q

Hemizygous

A

for sex-linked trait: carrier, normal, affected

123
Q

Important to note for sex-linked phenotype

A

List gender + phenotype

124
Q

Lethal allele

A

the homozygous genotype is lethal

125
Q

How to know if gene is linked or not

A

if phenotypic ratio varies from the expected, it is linked

126
Q

Down’s syndrome

A

extra copy of the 21 chromosome

127
Q

WZ/ZZ in what animals

A

some birds, some snakes (tiger), monitor lizards (goannas), amphibians (frog),

128
Q

Egg production in females called

A

Oögenesis

129
Q

Oögenesis how many eggs produced each stage

A

two then only one, two then only one

130
Q

Sperm production in males called

A

Spermatogenesis

131
Q

Spermatogenesis how many eggs produced in each stage

A

2, so four in total at end

132
Q

Asexual reproduction

A

production of genetically identical offspring from one parental organism only.

133
Q

Sexual reproduction

A

method of producing offspring that involves a genetic contribution (usually) from two parents, typically the fusion of a haploid egg and a haploid sperm to form a diploid zygote.

134
Q

Recombination

A

process of generating new combinations of alleles of various genes both by crossing over and by independent assortment during meiosis.

135
Q

Number of genes in each cell

A

21,000

136
Q

Mitochondrial genes

A

genes located in the DNA of mitochondria and transmitted in a matrilineal manner

137
Q

Multiple alleles

A

refers to three or more alleles of a specific gene

138
Q

Heterozygous

A

a cell/organism whose genotype for a particular gene comprises two different alleles

139
Q

Homozygous

A

cell/organism whose genotype for a particular gene comprises of two identical alleles

140
Q

Dominant

A

refers to a trait that is expressed in the heterozygous condition

141
Q

Recessive

A

refers to a trait that is only expressed in the homozygous form i.e. is not expressed in the heterozygous form.

142
Q

Sex-linked trait

A

refers to a trait which is controlled by a gene with its locus on a sex-chromosome

143
Q

Two types of sex-linked traits

A

x linked and y linked

144
Q

How to find out which trait is dominant

A

the phenotype of the heterzygote

145
Q

X-inactivation

A

random switching off of one gene of the two X-chromosomes present in somatic cells of mammalian females

146
Q

When does x-inactivation occur

A

during early embryonic development.

147
Q

Carrier

A

heterzygote that has the allele for the recessive trait but does not express the trait

148
Q

Co-dominance

A

relationship between two alleles of a gene, where the alleles are equally dominant, such that a heterozygous organism shows the expression of both alleles in its phenotype.

149
Q

Difference between co-dominance and incomplete dominance red/white flower

A

co-dominance would be red and white dots, incomplete dominance is pink flower

150
Q

The genotype + environment forms

A

the phenotype

151
Q

Why test crosses are used

A

to identify if organism showing a dominant trait is homozygous or heterozygous, establish linkage relationships

152
Q

To work out if a trait is dominant homozygous minimum organisms to be born

A

16

153
Q

Ways linked genes are represented

A

A b () a B, Ab/aB, A b (=) a B

154
Q

Test to work out if gene is linked

A

cross two heterozygotes

155
Q

If the gene is linked for heterozygous test, the ratio will be

A

9:3:3:1

156
Q

If it is not linked, the ratio for heterozygous test will be

A

1:1:1:1

157
Q

Gene assortment

A

independent distribution of unlinked genes to gametes as a result of the independent movement of non-homologous chromosomes carrying those genes to opposite poles during meiosis.

158
Q

Distance between loci formula

A

100*number of recombinant offspring/total number of offspring

159
Q

What did Mendel study

A

inheritance of variation in the traits

160
Q

What lead to Mendel’s success

A

one trait at a time, known history of parents, recording parentage, counting offspring

161
Q

What do large numbers of offspring allow (3)

A

egularities to be recognised and valid averages to be identified, to ‘ascertain their statistical relations’

162
Q

Mendel’s discoveries (7)

A

each trait controlled by a pair of inherited factors (alleles). For each trait individual plants had two factors that could be identical or different, plants with identical factors were referred to as pure breeding and plants with different factors were called hybrids. Each factor was a discrete particle and retained its identity across generations. Recessive and Dominant. One factor per gamete. Genes behaved independently. The results were the same regardless of plant was used as male/female.

163
Q

Transforming factor

A

substance that had the ability to change the genetic character of bacteria that was later identified as being DNA?

164
Q

Dissociation

A

separation of double-stranded DNA molecule into its single strands, which occurs when the hydrogen bonds stabilising the two strands are broken.

165
Q

Re-association

A

re-pairing of single strands of DNA during cooling after the two strands of a DNA double helix have been dissociated by heating.

166
Q

Hybridisation

A

pairing between single-stranded complementary DNA segments from organisms from the same or even different species.

167
Q

Genome

A

the full set of genes carried by an individual (or cell)

168
Q

Gene sequencing

A

identification of the order or sequence of bases along the DNA of a specific gene

169
Q

Decoded

A

refers to the translation of genetic information held in DNA into amino acids

170
Q

Encoded

A

refers to the holding of genetic information in DNA in coded form as a base sequence.

171
Q

Genomics

A

study of genomes

172
Q

Proteome

A

full set of proteins produced by a single cell or organism

173
Q

Single nucleotide polymorphism

A

when one base sequence varies.

174
Q

Opening reading frames

A

reading frames (codes) that can be transcribed

175
Q

Name of genes that result in proteins

A

protein-encoding genes

176
Q

Gene duplication

A

where a second copy if the DNA sequence of a gene appears in a genome.

177
Q

Gene action

A

processes of transcription and translation of a gene into a gene product.

178
Q

Transcription steps

A
  1. RNA polymerase attaches to a specific promotor sequence of DNA in the upstream region of the template strand. The double-stranded DNA of the strand unwinds and exposes the bases of the template strand.
  2. The base sequence of the DNA template guides the building of a complementary copy of the mRNA sequence. The RNA polymers enzyme moves along the DNA template in a 3’ to 5’ direction and, as it moves, complementary nucleotides are brought into place, and, one by one, are mined to form an RNA chain.
  3. After the RNA polymerase moves past the coding region and into the down-stream region of the gene, transcription stops and the mRNA molecule is released from the template. The result of this process is a single stranded molecule of pre mRNA.
179
Q

What happens after transcription

A

pre-mRNA is modified into mRNA

180
Q

What is modification of pre-mRNA called

A

post-transcription modification

181
Q

What happens in post-transcription modification

A

introns are cut out, poly-A tail added to 3’ end and a methyl cap is added to 3’ end

182
Q

How are introns spliced

A

spliceosomes

183
Q

Where does translation occur

A

ribosomes (cytoplasm)

184
Q

How are amino acids bought to mRNA

A

tRNA

185
Q

tRNA structure

A

tRNA consists of a strand of 76 nucleotides coiled and pairs with themselves. At one end of the tRNA molecule there are three bases that make up an anticodon, at the other end is a region that attaches to one specific amino acid

186
Q

What does amino acyl tRNA synthetase do

A

catalyses the linking of each amino acid to its specific tRNA carrier.

187
Q

Codon

A

sequences of 3 bases

188
Q

DNA is a… model

A

semi-conservative model

189
Q

Some genes are active only

A

in specific tissues

190
Q

Pre mRNA also known as

A

primary transcript

191
Q

Two steps in gene expression

A

transcription, translation

192
Q

RNA polymerase role

A

unwind DNA and synthesise an RNA strand complementary to the 3’-5’ direction of the gene

193
Q

G1 phase

A

cell grows in size, duplicating its organelles, synthesised proteins required for S phase

194
Q

G2 phase

A

grows in size again, and synthesising proteins for M

195
Q

M

A

mitosis/meiosis

196
Q

DNA replication

A
  • DNA helicase unwinds DNA
  • primer is synthesised by RNA/DNA primes
  • DNA polymerase synthesises a new DNA strand starting from the primers (5’-3’) small segments backwards (Okazaki fragments)
  • leading strand? lagging strand?
  • DNA ligase join fragments in each strand to form DNA strand
197
Q

Silent mutations

A

no change in amino acid sequences

198
Q

Missense mutations

A

replacement of one amino acid with another

199
Q

Nonsense mutations

A

mutated into a stop codon

200
Q

Gene amplifications

A

segments of DNA are repeated again

201
Q

Prophase 1

A

chromatin shortens and thickens into small and compact chromosomes, the spindle forms the centrosomes around the cycles and approaches the nucleus, the chromosomes line up in their homologous chromosomes and cross over, the nuclear membrane breaks down

202
Q

Metaphase 1

A

spindle fibres attach to the centromeres of each homologous chromosome, the tetrads line up in a plane in the middle of the cell

203
Q

Anaphase 1

A

the spindle contracts, separating each tetrad back into the double stranded chromosomes, and the double stranded chromosomes migrate to opposite poles of the cell attached to the spindle

204
Q

Telophase 1

A

chromosomes uncoil and become less compact, two nuclear membranes reform,

205
Q

Meiosis 2 stages are the same as…

A

mitosis 1 stages

206
Q

Identical twins are also known as

A

monozygotic twins

207
Q

Genotypic ratio

A

expected ratio of offspring with each possible genotype

208
Q

Phenotypic ratio

A

expected ratio off offspring with each possible phenotype

209
Q

Difference between prokaryote and eukaryotes chromosomes

A

Prokaryotes are circular, eukaryotes are linear

Prokaryotes don’t have introns

Prokaryotes lack histones

Year 12 Biology (9 decks)

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