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Genetics Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is classification?

A

Placing objects into similar groups or categories

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2
Q

How are things classified?

A

Similarities in structure, function and development

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3
Q

What is the basic unit of classification?

A

Species

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4
Q

What is a species?

A

Group of similar organisms that are capable of naturally interbreeding with eachother to produce fertile offspring

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5
Q

What is variation within a species?

A

In a group of successfully interbreeding organisms, the individual members show different characteristics

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6
Q

How can members within a species differ in humans and plants

A

Human - hair colour, skin colour, height

Plant - flower colour, leaf shape

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7
Q

What is acquired variation and give an example

A

Not inherited/not genetically controlled and therefore learned and developed
Eg, ability to speak language, learn piano

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8
Q

What is inherited variation and give an example

A

Controlled by genes eg, ear shape

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9
Q

What is heredity?

A

It’s the passing on of features from parents to offspring by means of genes

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10
Q

What are the units of heredity?

A

Genes

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11
Q

What are characteristics?

A

Traits/features that are inherited genetically

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12
Q

What are genes?

A

Section of DNA that can cause production of protein

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13
Q

The proteins produced by genes are mainly what?

A

Enzymes

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14
Q

Why/how do genes control a cell

A

Enzymes they produce control cell activities

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15
Q

Where in the nucleus would you find genes?

A

On a Chromosome

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16
Q

What is gene expression?

A

It’s the precise way in which the genetic information in a gene is decoded in the cell and used to make protein

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17
Q

What are chromosomes composed of?

A

Protein and DNA

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18
Q

What protein is present in chromosomes?

A

Histone

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19
Q

What is the role of protein in chromosomes?

A

It’s responsible for holding DNA in a tightly packed configuration so it can fit nucleus

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20
Q

What is the function of non-coding dna

A

It is not known - it’s known as “junk DNA”

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21
Q

Name the key chemical that is inherited by organisms

A

Genes

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22
Q

What is coding and non coding DNA

A

Coding - DNA capable of gene expression to produce protein

Non-coding DNA - not capable of gene expression to produce protein

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23
Q

Where in the cell would you expect to find most DNA?

A

Nucleus

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24
Q

Name the four bases that are found in DNA

A

Cytosine, Guanine, Adenine, Thymine

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25
Q

What is meant by a triplet code?

A

Sequence of three bases which codes for one specific protein

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26
Q

The triplet code is transcribed into mRNA. What does this statement mean?

A

Info [code] is copied from DNA to RNA

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27
Q

To which structures in the cell does mRNA carry the code?

A

Ribosome

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28
Q

Which base can link only to thymine?

A

Adenine

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29
Q

Which base can link only to cytosine?

A

Guanine

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30
Q

Name the type of bonding which occurs between members of a base pair

A

Hydrogen bonding

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31
Q

Explain what is meant by the term DNA profiling

A

Examining DNA for a pattern/band to compare
Method of making a unique pattern of bands from the DNA of a person, which can then be used to distinguish that DNA from other DNA

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32
Q

Give two applications of DNA profiling

A

Forensic [identify criminal]

Maternity/paternity determination

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33
Q

What is genetic screening?

A

Testing DNA for the presence or absence of altered/abnormal genes

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34
Q

The same amount of DNA is present in the nuclei of cells taken from the liver, heart, pancreas and muscle of a rat.
Use your knowledge of DNA and mitosis to explain this statement

A

Chromosome contains DNA

Mitosis maintains same chromosome number

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35
Q

The same amount of DNA is present in the nuclei of cells taken from the liver, heart, pancreas and muscle of a rat.
Name a dell produced by the rat which will contain a different amount of DNA in its nucleus to those mentioned above

A

Gamete

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36
Q

Give a brief account of the stages involved in DNA profiling

A

DNA released
DNA cut into fragments by restriction enzymes
Fragments separated on basis of size of gel
Pattern analysed

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37
Q

Labelled diagram of a nucleotide

A

Check notes

Phosphate, deoxyribose, base

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38
Q

What part of a nucleotide may vary from nucleotide to nucleotide

A

Base

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39
Q

What is meant by non-coding DNA

A

Does not code for protein

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40
Q

Give one structural difference between DNA and RNA

A

DNA - thymine

RNA - uracil

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41
Q

Name a cell organelle apart from the nucleus in which DNA is found

A

Mitochondria

Chloroplast

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42
Q

Describe fully the roles played in protein synthesis by the three different types of RNA

A

mRNA - gets code from DNA and carries code to ribosome
rRNA - binds mRNA in place for translation
tRNA - transfers amino acids to mRNA to ribosomes

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43
Q

Once a protein has been sythesised, a final step is required for it to become fully functional. What is this step?

A

Folding

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44
Q

Write notes on the following topics in relation to nucleic acids

i) Complementary Base Pairs
ii) Codons
iii) Transcription

A

i) Two bases joined by hydrogen bonds, Adenine bonds to Thymine and Cytosine bonds to Guanine in DNA, in RNA thymine is replaced with Uracil
ii) sequence of three bases which codes for one specific amino acid/protein in DNA
iii) mRNA is formed using single strand of DNA, catalysed by RNA polymerase

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45
Q

Name the biomolecule that is the major component of meat

A

Protein

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46
Q

Where in the cell are protein manufactured?

A

Ribosomes

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47
Q

Name the molecule formed from DNA, which carries the instruction to manufacture proteins

A

mRNA

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48
Q

Name the procedure used for analysing the DNA samples that revealed the presence of horse meat in products labelled as beef

A

DNA Profiling

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49
Q

Would the result from DNA Profiling be the same if beef were contaminated with pig meat

A

No, because pig DNA is not same as Horse DNA

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50
Q

What are the subunits of nucleic acid found in DNA?

A

Nucleotides

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51
Q

How are the strands of a DNA molecule joined together?

A

Hydrogen Bonds

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52
Q

What are the two main events in the replication of DNA

A

DNA opens and new strands of DNA are made

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53
Q

Explain the term transcription

A

Making mRNA using DNA (template)

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54
Q

Explain the term translation

A

Making protein using code from mRNA [RNA template]

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55
Q

In which structures in the cell does translation occur?

A

Ribosomes

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56
Q

How many bases in sequence make up a codon in mRNA

A

Three

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57
Q

Each mRNA codon specifies one of three possible outcomes during protein synthesis. Name these three possible outcomes

A

Start, adding an amino acid, stop

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58
Q

What does the letter ‘t’ stand for in tRNA?

A

Transfer

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59
Q

During translation, what are attached usually to the two ends of the tRNA molecules

A

mRNA codon and an amino acid

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60
Q

What percentage of chromosomes are DNA?

A

40%

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61
Q

How do two strands of DNA match up?

A

Specific base pairing between just four bases

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62
Q

What are the

i) two purines
ii) two pyramidines

A

i) adenine, guanine

ii) thymine, cytosine

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63
Q

Strands of DNA are anti-parallel, what does this mean?

A

Strands of DNA run parallel to each other but in opposite directions

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64
Q

What is another word for non-coding DNA?

A

Introns

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65
Q

What percentage of DNA is non-coding?

A

97%

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66
Q

What is another word for coding DNA?

A

Exons

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67
Q

What are the differences between RNA and DNA

A 
DNA - 
Sugar -> Deoxyribose
Thymine instead
Double stranded 
RNA -
Sugar -> Ribose
Base uracil instead
Single stranded
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68
Q

Give two examples of genetic disorders

A

Cystic fibrosis

Albanism

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69
Q

How is genetic screening used for adults?

A

Although they do not suffer from a genetic disorder they may carry a defective gene that may want to find out if they are a carrier of that gene or not

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70
Q

What are the ethical reasons behind genetic screening?

A

Is it better to be prepared for disorder?

Would person wish to know if they have a genetic disorder that will develop on later years?

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71
Q

When does DNA replication occur?

A

Interphase of cycle

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72
Q

Describe the events that occur in the replication of DNA

[look at page]

A

The double helix uncoils [rope-ladder]
Enzyme breaks the bonds between the base pairs
DNA bases that are naturally present in cytoplasm enter the nucleus. The incoming bases attach to the exposed complementary bases. In this way, each side of the DNA molecule acts as a template for the new DNA that is formed
Each new strand is half new and half old and identical to the original DNA strand and to the other new partner strand
Each new piece of DNA rewinds to form a double helix

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73
Q

What occurs during transcription in protein synthesis

A

DNA is uncoiled and separated by enzymes in nucleus
Complementary RNA bases [A,U,G,C] bond with one of the exposed DNA strands
RNA polymerase joins with RNA bases together to form mRNA
Each mRNA carries a start codon, a series of codons to form specific amino acids, a stop codon

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74
Q

What occurs during translation in protein synthesis

A

mRNA moves from the nucleus to the cytoplasm
Ribosomes are made of rRNA and protein
The mRNA bonds weakly with the rRNA in the ribosome
tRNA carries a special triplet [anti-codon] and an amino acid [AA6, AA12]
tRNA attaches to the mRNA [each anticodon pairs up with the complementary codon on the mRNA, bringing an amino acid to ribosomes]
The tRNA lines up along the mRNA strand and each adjacent amino acid join up to form a protein chain. The amino acids detach from the tRNA
tRNA leaves the ribosome without aa’s pulling the mRNA with it allowing the mRNA sequence to be completed and a new protein being formed until the stop codon is reached
A protein is made when the stop codon is reached [synthesised]. This protein undergoes further folding to reach the correct shape of that protein

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75
Q

What is the site of protein synthesis

A

Ribosome

76
Q

Where is mRNA found?

A

Nucleus, cytoplasm and ribosome

77
Q

Where is tRNA found?

A

Cytoplasm

78
Q

Where is rRNA found?

A

Ribosome [where proteins are made]

79
Q

Describe the method you took when you isolated DNA from plant tissue

A

Sodium chloride was added to washing up liquid and distilled water was added to 100cm^3
Cut onion into small cubes and add to beaker and stir
Put beaker in water bath for 15 mins @ 60
Cool mixture in ice water bath 5 mins, stirring frequently
Pour mixture in blender and blend for 3 seconds
Filter mixture with coffee filter paper in second beaker [don’t add foam]
Syringe [no needle] used to place onion filtrate into boiling tube
Add protease enzyme [pepsin] to boiling tube and mix well
Pour ice-cold ethanol down side of boiling tube and the ethanol will form a layer on onion filtrate
Twist glass rod with wire loop in alcohol and the strands of DNA should attach to rod.

80
Q

-isolate DNA-

Why must you chop the onion to small pieces

A

Physical chopping breaks the cell walls and allows the cytoplasm to leak out

81
Q

-isolate DNA-

Why is washing up liquid added?

A

Breaks down lipids in phospholipid bilayer and causes protein in the membranes to break apart. This results in the release of the nuclear material from the cell

82
Q

-isolate DNA-

Why is salt added?

A

To minimise the attractive forces present between DNA and protein by shielding the DNA molecules causing them to clump together

83
Q

-isolate DNA-

Why is the mixture heated to 60 degrees for exactly 15 minutes

A

Causes DNases, released from lysosomes to be broken down

84
Q

-isolate DNA-

What happens if the mixture is heated for more than 15 minutes

A

DNA itself will be broken down

85
Q

-isolate DNA-

Why is the mixture cooled?

A

Decreases the rate of chemical reactions, slowing the action of any remaining enzymes before they destroy the DNA

86
Q

-isolate DNA-

What is the function of blending?

A

Further destroys cell walls and membranes, causes DNA to be released

87
Q

-isolate DNA-

What occurs if the mixture is blended for more than three seconds?

A

It shears the fragile DNA strands

88
Q

-isolate DNA-

Why is protease added?

A

Breaks down proteins associated with DNA

89
Q

-isolate DNA-

What is the mixture filtered with?

A

Coffee filter paper

90
Q

-isolate DNA-

What is the purpose of filtering?

A

Strains all the large cellular debris out of the mixture. DNA is passed through the filter with the liquid

91
Q

-isolate DNA-

Why is cold ethanol used?

A

Forms a layer on top of the onion filtrate and tends to draw water out of DNA molecule making it less dense. DNA is insoluble in cold ethanol

92
Q

-isolate DNA-

Where are the DNA strands found in the mixture?

A

Interface of the two liquids

93
Q

The son of a haemophiliac father was not haemophiliac. Explain in detail how this situation might have arisen

A

The haemophilia gene is recessive and sex linked
The father has to be XYn- and the son doesn’t have haemophilia meaning he has to be XYN-
The mother can be XXNN or XXNn
Son would get XN from egg and Y- from sperm meaning he does not haemophilia

94
Q

In genetics what is meant by sex-linkage

A

Genes are carried on the sex chromosomes

95
Q

Would human females or males be more likely to suffer from sex linked diseases such as haemophilia. Explain your answer by referring to possible genotypes and corresponding phenotypes

A 
Males 
Males - XYn- sufferer
Females - XXnn sufferer
XXNn normal 
Males only needs to inherit recessive allele and female needs both recessive alleles from each parent
96
Q

In certain breed of cattle there is incomplete dominance between alleles for red coat and allele for white coat. The heterozygous individuals are roan. In each of the following write the percentage chance it will have a red coat
i Roan x White
ii)Roan x Red
iii)Roan x Roan

A

i) Rr x rr = O%
ii) Rr x RR = 50%
iii) Rr x Rr = 25%

97
Q

Which famous 19th Century biologist is regarded as “the father of genetics”

A

Mendel

98
Q

In genetics what is meant by segregation

A

Separation of homologous chromosomes

99
Q

Give two examples of sex-linked characteristic in humans

A

Haemophilia, colour-blindness

100
Q

Two heterozygous chromosomes, one male and one female. Which will produce the greatest number of different gametes

A

Female
Sex
Combinations

101
Q

Write out genotypes of gametes that the bird with gl linked and gl linked who is a man

A

Xgl Ygl

102
Q

What term is used to describe the allele pair Pp and is this a sex-linked condition?

A

Heterozygous

No, genes are not carried on x or Y chromosomes

103
Q

[cattlee breed where P = hornless is dominant to horned]

Draw a chromosome diagram when crossed with Pp XY would ensure the production of a hornless calf

A

PP XX

104
Q

Name a group of organisms in which XY chromosome pair gives rise to a different sex in cattle

A

Birds, Butterflies, Moths

105
Q

Human males and females differ in one of their twenty three pairs of chromosomes. What name is given to this pair of chromosomes

A

Sex chromosomes / Heterosomes

106
Q

Draw the two sex chromosomes for human male and human female

A

Male - XY I short I

Female - XX II

107
Q

Using a punnet square, that a child stands an equal chance of being male or female

A

X Y
X xx xy
X xx xy

XX, XX, XY, XY
50% 50%

108
Q

[The allele for smooth is dominant to wrinkled and the allele for yellow is dominant to green]
Give genotype of pea plant that’s homozygous in respect to seed texture and heterozygous in respect of seed colour

A

SSYy

Smooth and yellow

109
Q

Give another genotype which will produce the same phenotype as SsYy

A

SSYY

110
Q

The allele for smooth is dominant to wrinkled and the allele for yellow is dominant to green
Allele for smooth is linked to allele for green and the allele for wrinkled were linked together yellow give the genotypes of two gametes that parent SSYy can produce

A

Sy

sY

111
Q

What is the significance of the fact that the two allele pairs are located on different chromosome pairs

A

Independent assortment can occur

112
Q

What is an allele?

A

Different form of same gene

113
Q

What is homozygous

A

Two identical alleles

114
Q

What is heterozygous

A

Two alleles are different of a gene

115
Q

What is linkage?

A

Genes on same chromosome

116
Q

What is a locus?

A

Position of a gene on a chromosome

117
Q

What is a dominant allele

A

Allele that prevents the working of the recessive allele/who masks the expression of recessive

118
Q

What is a recessive allele

A

Allele is prevented from working by a dominant allele/whose expression is masked by dominant

119
Q

What is a genotype

A

Genetic make up of an organism

120
Q

What is a phenotype

A

Physical make up of an organism which is the expression of the genotype

121
Q

What is the progeny

A

Offspring produced

122
Q

What is haploid and diploid

A

Haploid - nucleus with 1 set of chromosomes

Diploid - nucleus with two sets of chromosomes

123
Q

What term is used to describe alleles that lie on the same chromosome?

A

Linked

124
Q

How many loci are marked in the diagram

Linked AB and ab, non-linked Dd and Cc

A

4 (each pair of allele is one locus)

125
Q

How do you know whether or not alleles are linked?

A

on same chromosome or not

126
Q

Suggest why a person with a heterozygous allele pair does not suffer from the condition

A

Dominant allele masks expression of recessive allele

127
Q

Parents who are suspected of being carriers of disease-causing alleles may be advised to consider a genetic test. Suggest a role for such test after in-vitro fertilisation

A

Selection of embyro

128
Q

Explain why linked genes do not assort independently

A

They are transmitted together on same chromosome

129
Q

What term is used to describe a person who has a gene for colour blindness but who does not exhibit the condition

A

Carrier

130
Q

If a colour blind father and a mother who is heterozygous for this condition, is it possible to have a colour blind daughter and briefly explain your answer

A

Yes, both parents carry gene for colour blindness

131
Q

Where is mRNA found

A

The nucleus and cytoplasm in a cell

132
Q

Is down syndrome a condition caused by a gene mutation

A

No, it occurs due to a change in chromosome number

133
Q

Where does transciption occur in a cell

A

Nucleus of cell

134
Q

Explain the significance of DNA replication

A

Exact copies of DNA is passed from generation to generation

135
Q

Name an enzyme involved in transcription

A

RNA polymerase

136
Q

What do tRNA molecules carry to aid this process

A

Anticodon

137
Q

Why is it necessary for folding to occur once the protein has been formed

A

Correct shape needed to carry out function

138
Q

Are somatic cells diploid or haploid

A

Diploid - contain two of each type of chromosome

139
Q

What produces the phenotype?

A

Interaction of genes with environment

Genotype + environment = phenotype

140
Q

What are monohybrid crosses

A

Involves the study of a single characteristic

141
Q

What are autosomes and how many do we have?

A

Non-sex chromosomes

44

142
Q

How many chromosomes do we have and how many are sex chromosomes?

A

46 chromosomes

Two sex chromosomes

143
Q

How is the sex of a child determined

A

Genotype of the sperm that fertilises the egg

[fathers sperm that determines the sex of the child]

144
Q

What are dihybrid crosses?

A

Study of two characteristics at the same time

145
Q

Why is haemophilia more common in males than in females

A

Males need only single recessive allele to be haemophiliac whereas females need two recessive alleles

146
Q

What is Mendel’s second law? [Law id Independent Assortment]

A

It states that when gametes are formed either pair of the alleles is equally likely to combine with either of another pair of factors

147
Q

What is Mendels first law? [Law of Segregation]

A

Inherited characteristics are controlled by pairs of factors, these factors segregate from each other at gamete formation, with only one member of the pair being found in each gamete

148
Q

What is genetic engineering?

A

Artificial manipulation or alteration of genes

149
Q

Give an example of genetic engineering in a

i) plant
ii) animal
iii) micro organisms

A

i) gene for vitamin A from daffodil is inserted into rice
ii) gene for human growth hormone from human inserted into cows milk
iii) gene for human insulin is inserted into bacterium e.coli

150
Q

What are the four tools for genetic engineering

A

Source of DNA [cell containing target gene]
A cloning vector [bacterial plasmid]
Restriction enzymes [cut bases at specific base sequences]
DNA ligase [pasting DNA]

151
Q

What are the five processes in genetic engineering?

A 
Isolation
Cutting
Ligation
Transformation
Expression
152
Q

What occurs in isolation in genetic engineering

A

Target gene on its chromosomes must be released from the donor cell
Plasmid must be released from bacterial cell

153
Q

What occurs in cutting in genetic engineering

A

Plasmid DNA cut by restriction enzymes at specific base sequences
The chromosome with target gene gets cut many times by same restriction enzyme at same base sequence

154
Q

What occurs in ligation in genetic engineering

A

Enzyme DNA ligase used to join up target gene DNA with plasmid DNA. The ends match due to the fact both DNA’s are cut by same enzymes

155
Q

What occurs in transformation of genetic engineering

A

The host DNA is now different - or “transformed”

156
Q

What occurs in expression of genetic engineering

A

Gene is expressed once protein is produced on target gene

157
Q

Give two ethical/moral issues surrounding genetic engineering

A

Release of GMO’s into environment -> it genetically modified plants are grown outdoors, there are fears that foreign genes they contain might spread to other plants
Genetic engineering in humans -> inserting/removing gene from sperm or eggs and zygotes is at present not acceptable, form of eugenics

158
Q

In the context of natural selection, explain how numbers in a population remain relatively constant despite the production of many offspring

A

Competition
Best adapted to survive
Death rate equals reproductive rate

159
Q

Outline the role of natural selection in evolution

A

Better adapted to survive and this adaption is inherited

160
Q

Explain the term mutation

A

Change in amount of structure of DNA

161
Q

Give one example of a disorder caused by gene mutation

A

Sickle cell anaemia

162
Q

Give one example of a disorder caused by chromosome mutation

A

Down syndrome

163
Q

Give one cause of the differences which exist between individuals of a species

A

Sexual reproduction
Meiosis
Independent Assortment
Mutations

164
Q

Give a source of evidence for evolution and briefly outline the evidence

A

Fossils - change over time which allows to be compared
Study of embryos [embryology] -the greater the similarity in structure, the more closely related the species are and the more recent their common ancestor is.

165
Q

Name two types of mutation

A

Gene mutation

Chromosome mutation

166
Q

Name two agents responsible for increased rates of mutation

A

[mutagens]
UV light
X-rays

167
Q

Briefly explain the significance of mutation in relation to natural selection

A

New phenotypes = better adapted

168
Q

Name the scientists responsible for the theory of natural selection

A

Darwin and Wallace

169
Q

What is meant by variation?

A

Differences between individuals of the same species

170
Q

What is the significance of inherited variation in the evolution of species

A

Inherited variation which produces new genotypes allows natural selection to occur and thus evolution

171
Q

Give an account of the Theory of Natural Selection. Name the scientists who are associated with the theory and refer to any one observation that promotes its development

A

A species produces a large number of offspring and has a high reproductive rate
Then, the population of the organisms remain constant due to competition or the struggle for survival and the environment no longer able to support them
Some organisms show genetic variation because of sexual reproduction [breeding] which are passed on
Darwin and Wallace
Observation - population no’s remain constant

172
Q

-isolate DNA-

What is a protease enzyme?

A

Breaks down protein

173
Q

-isolate DNA-

The final separation of the DNA involves the use of alcohol [ethanol]. Under what conditions is the alcohol used

A

Ice cold

174
Q

How does meiosis cause inherited variation

A

Human cells have 46 chromosomes with millions of combinations of chromosomes

175
Q

How are mutations inherited?

A

Mutations may be inherited by zygote and passed onto all the cells in the child

176
Q

What are mutagens

A

Agents that cause mutations

177
Q

Give an example of a mutation caused by mutagens

A

Tobacco smoke - causes mutations in a gene called P53

178
Q

How does one protect against mutations

A

X-rays - wear heavy lead shield to absorb xray

UV rays - wear high sun protection factor

179
Q

What is sickle cell anaemia

A

Example of gene mutation

Inherited blood disorder caused by a mutation in the haemoglobin gene

180
Q

What is evolution?

A

The way in which living things change genetically to produce new forms of life over long periods of time

181
Q

What is the conclusion drawn from overbreeding

A

Struggle for existence [competition]

182
Q

What is the conclusion drawn from population no’s remaining constant

A

Natural selection

183
Q

What is the conclusion drawn from inherited variations occur in population

A

Natural selection

184
Q

What is natural selection

A

Process by which organisms with genetically controlled characteristics that allow them to be well adapted to their environment will survive and reproduce to pass on their genes to following generations

185
Q

Give an example of evolution

A

Evolution of horse
60 million years ago - ancestor was size of fox
30 million years ago - size of german Shepard
15 million years ago - size of Great Dane

Biology (36 decks)

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