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chapter 13 meiosis and sexual life cycles Flashcards

1
Q

What is the 3rd largest group of flowering plants?

A

Legumes

Over 18,000 species worldwide.

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2
Q

What distinguishes legumes?

A

Seed pods seamed on two sides.

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3
Q

What is the beneficial relationship between legume plants and nitrogen-fixing bacteria called?

A

Legume-Rhizobia symbiosis.

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4
Q

What is the main component of synthetic fertilizers?

A

Nitrogen.

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5
Q

What percentage of nitrogen is typically lost to the atmosphere or leaching from synthetic fertilizers?

A

30-50%.

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6
Q

What are the two main types of DNA sequences in a genome?

A

Coding and non-coding.

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7
Q

What is the definition of a genome?

A

Organisms complete set of DNA (or RNA in many viruses).

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8
Q

How many base pairs does the human genome contain?

A

Over 3 billion.

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9
Q

What percentage of the human genome consists of protein-coding genes?

A

2%.

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10
Q

What is the largest known genome of any vertebrate?

A

Marbled lungfish with 130 million base pairs.

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11
Q

What is a gene?

A

Molecular unit of heredity.

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12
Q

What do alleles represent?

A

Variant forms of the same gene.

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13
Q

What is the old hypothesis regarding genes and proteins?

A

One gene = one mRNA = one protein.

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14
Q

True or False: GMOs are the same as mutants.

A

False.

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15
Q

What is heredity?

A

Transmission of traits (genes) from one generation to the next.

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16
Q

What is the definition of a clone?

A

Group of genetically identical individuals.

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17
Q

What is a gamete?

A

Cell that fuses with another cell to form a new organism.

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18
Q

How many chromosome pairs do human somatic cells have?

A

23 pairs.

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19
Q

What are sex chromosomes in humans?

A

X and Y chromosomes.

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20
Q

What is the diploid number of chromosomes in humans?

A

46.

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21
Q

What are identical twins formed from?

A

One egg fertilised by one sperm.

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22
Q

What occurs during meiosis 1?

A

Homologous chromosomes pair up and separate.

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23
Q

What is crossing over?

A

Homologous chromosomes physically connect and exchange genetic information.

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24
Q

What is the outcome of meiosis 2?

A

Four haploid daughter cells containing un-replicated chromosomes.

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25
What does mitosis produce?
Two genetically identical daughter cells.
26
What is the original source of genetic diversity?
Mutations.
27
What is a single nucleotide polymorphism (SNP)?
A substitution of a single nucleotide at a specific position in the genome.
28
What are the three main mechanisms that contribute to genetic variation?
* Independent assortment of chromosomes * Crossing over * Random fertilisation
29
What does independent assortment of chromosomes refer to?
Homologous pairs orient randomly at metaphase 1 of meiosis.
30
What is the significance of crossing over?
Combines DNA inherited from each parent, producing recombinant chromosomes.
31
What is the evolutionary significance of genetic variation?
Natural selection results in the accumulation of genetic variations favoured by the environment.
32
What are genes?
Segments/regions within genomes that encode something
33
What are non-coding elements in the genome?
* Junk DNA * Viruses * Repeat sequences * Transposable elements
34
What types of genomes exist?
* Prokaryotic (bacterial and viral) * Eukaryotic (nuclear genome) * Organelle genomes (mitochondrial and chloroplast)
35
What is a chromosome?
A long DNA molecule containing part or all of the genetic material of an organism
36
What does genomics study?
Properties of a genome, often in comparison with other species
37
What does genetics study?
Properties of one or more genes to understand heredity and variation
38
When were the first genomes sequenced?
In the 70s and 80s for viruses, and in the 90s for bacteria and yeast
39
How many total chromosomes does the human genome have?
46 total (22 paired chromosomes plus X and Y)
40
What is the total number of base pairs in the human genome?
Over 3 billion base pairs
41
What is the largest known genome of any vertebrate?
Marbled lungfish (Protopterus aethiopicus) with 130 billion base pairs
42
What is the largest genome of any plant?
Canopy plant (Paris japonica) with 149 billion base pairs
43
Fill in the blank: Genes specify proteins via _______ and translation.
transcription
44
Is the genetic code universal?
True
45
What is the difference between GMOs and mutants?
* GMOs: generated in the lab with new DNA introduced * Mutants: involve the organism’s own DNA and occur naturally
46
Define heredity.
Transmission of traits (genes) from one generation to the next
47
What is variation in genetics?
Differences in offspring from parents and siblings
48
What is a somatic cell?
xAny cell other than a gamete
49
What is a karyotype?
An ordered display of chromosome pairs from a cell
50
What are homologous chromosomes?
Two chromosomes in each pair that are similar in shape and size
51
How many pairs of sex chromosomes do human females have?
One pair (XX)
52
How many pairs of autosomes do humans have?
22 pairs
53
What is a haploid cell?
A cell containing a single set of chromosomes
54
What is fertilization?
Union of gametes
55
What percentage of births in Australia are multiple births?
1.5%
56
What are maternal twins?
One egg fertilized by one sperm that divides into two individuals
57
What are paternal twins?
Two eggs fertilized by two sperm, resulting in non-identical individuals
58
What is the main outcome of meiosis?
Meiosis reduces the number of chromosome sets from diploid to haploid
59
What occurs during interphase in gamete formation?
Chromosomes duplicate forming sister chromatids
60
What are the two main stages of meiosis?
Meiosis I and Meiosis II
61
What is the result of Meiosis I?
Two haploid daughter cells containing replicated chromosomes
62
What is the result of Meiosis II?
Four haploid daughter cells containing un-replicated chromosomes
63
What happens to sister chromatids during meiosis?
Sister chromatids are genetically identical and joined at the centromere
64
List the four phases of Meiosis I.
* Prophase I * Metaphase I * Anaphase I * Telophase I and cytokinesis
65
What occurs during Prophase I?
Chromosomes condense and homologous chromosomes pair up
66
What is synapsis in meiosis?
Homologous chromosomes physically connect and exchange genetic information
67
What occurs during Metaphase I?
Paired homologs line up at the metaphase plate
68
What happens during Anaphase I?
Pairs of homologous chromosomes separate
69
What is cytokinesis?
Process of cell division that forms two haploid daughter cells
70
List the four phases of Meiosis II.
* Prophase II * Metaphase II * Anaphase II * Telophase II and cytokinesis
71
What occurs during Prophase II?
A spindle apparatus forms and chromosomes move toward the metaphase plate
72
What is the significance of crossing over during Meiosis I?
It produces genetically unique sister chromatids
73
What happens during Anaphase II?
Sister chromatids separate and move toward opposite poles
74
How does mitosis differ from meiosis?
Mitosis conserves the number of chromosome sets; meiosis reduces them in half
75
What is the original source of genetic diversity?
Mutations
76
What are alleles?
Different versions of genes created by mutations
77
What is a single-nucleotide polymorphism (SNP)?
A substitution of a single nucleotide at a specific position in the genome
78
What are homeotic genes responsible for?
Controlling pattern information in development
79
What does the bicoid gene affect?
The front half of the body
80
What is supernodulation?
A phenotype resulting from mutations in the regulation of nodule number
81
What is brachydactyly type D?
Clinically known as clubbed thumb
82
What is situs inversus?
Condition where major visceral organs are mirrored or reversed
83
List the three main mechanisms that contribute to genetic variation.
* Independent assortment of chromosomes * Crossing over * Random fertilization
84
What is independent assortment of chromosomes?
Homologous pairs orient randomly at metaphase I of meiosis
85
How many possible combinations of chromosomes are there for humans?
More than 8 million (2^23)
86
What is the effect of random fertilization on genetic diversity?
Produces a zygote with about 70 trillion diploid combinations
87
What role does natural selection play in evolution?
Results in the accumulation of genetic variations favored by the environment
88
True or False: Sexual reproduction does not contribute to genetic variation.
False

AGRC1021 (7 decks)

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