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12 Biology > Term 1 Biology Test > Flashcards

Term 1 Biology Test Flashcards

Ch 2 - 7 (83 cards)

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1
Q

What is an allele?

A

One of various versions of the same gene (at the same locus) distinguished by small differences in the DNA sequence

Alleles can result in different traits in an organism.

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2
Q

Define apoptosis.

A

A programmed series of events that leads to cell death (as a result of the dismantling of the internal contents of the cell by various enzymes, including caspases)

Apoptosis is crucial for development and maintaining homeostasis.

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3
Q

What is asexual reproduction?

A

The process by which a single parent produces offspring and that does not involve fusion of gametes; a process that usually results in identical offspring

Examples include binary fission in bacteria and budding in yeast.

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4
Q

What is an autosome?

A

A chromosome that is not a sex chromosome

Humans have 22 pairs of autosomes and one pair of sex chromosomes.

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5
Q

What is annealing in PCR?

A

The process of joining separate strands of DNA together as a result of hydrogen bond pairing; it occurs when the temperature is lowered.

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6
Q

What defines a blunt end in DNA?

A

The end of a DNA fragment created following cleavage by a restriction enzyme that cuts DNA at the same position on both strands.

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7
Q

What is the role of DNA ligase?

A

An enzyme used to catalyse the formation of a bond between two pieces of DNA.

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8
Q

What does DNA polymerase do?

A

Synthesises new strands of DNA based on a template strand and according to complementary base-pair rules.

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9
Q

What is DNA profiling?

A

A process that identifies natural variations within individual genomes, using STRs, PCR, and gel electrophoresis.

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10
Q

What is DNA sequencing?

A

The process of establishing the nucleotide sequence of a piece of DNA.

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11
Q

What is gel electrophoresis?

A

A technique that separates large molecules according to their size and charge for visualisation and identification.

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12
Q

What is gene cloning?

A

The process of using plasmids and bacteria to make numerous identical copies of a gene.

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13
Q

What is gene expression?

A

The translating of a gene into a protein by an organism; the phenotype is directly affected by gene expression.

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14
Q

What is a gene probe?

A

A specific short length of single-stranded DNA that can bind to a particular gene of interest.

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15
Q

What is genetic engineering?

A

Manipulation of genetic material to suppress or enhance a gene’s activity, or combine genetic material from different species.

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16
Q

What is a genetic marker?

A

A nucleotide sequence associated with a specific trait; may include short DNA sequences or whole genes.

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17
Q

What defines a transgenic organism?

A

An organism modified by incorporating a piece of foreign DNA into its genome.

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18
Q

What is a genome?

A

All of the genetic material contained in an organism or a cell, including chromosomes and DNA in mitochondria and chloroplasts.

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19
Q

What is linkage mapping?

A

Using frequencies of genes that cross over together to determine the relative positions of genes on a chromosome.

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20
Q

What is a molecular size marker?

A

A piece of DNA of known length used alongside samples in a gel to estimate the size of DNA fragments.

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21
Q

What is next-generation sequencing (NGS)?

A

An automatic process that finds the order of nucleotides in DNA, detected by a laser during electrophoresis.

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22
Q

What is a plasmid?

A

A small circular piece of DNA, found in bacteria, replicating independently of the cell’s chromosomes.

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23
Q

What is polymerase chain reaction (PCR)?

A

A cyclic method used to rapidly amplify small amounts of DNA into large amounts for laboratory use.

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24
Q

What is a primer?

A

A short fragment of single-stranded nucleic acid that marks where elongation/synthesis should start.

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25
What is a recognition site?
A specific sequence of DNA at which a restriction enzyme will cut.
26
What is recombinant DNA technology?
Tools and techniques used to transfer a gene from one species to the genome of another.
27
What is a recombinant plasmid?
A plasmid with foreign DNA inserted into it.
28
What is a restriction enzyme?
An enzyme that cuts DNA at a specific restriction site.
29
What is a short tandem repeat (STR)?
A short non-coding region of DNA that is repeated many times in the genome and is highly variable between individuals.
30
What defines a sticky end in DNA?
The end of a DNA fragment created when a restriction enzyme cuts DNA at different positions on each strand.
31
What is transformation in genetics?
The process of taking DNA from one organism and inserting it into another organism to obtain a desired characteristic.
32
What are variable nucleotide tandem repeats (VNTRs)?
Short non-coding regions of DNA that are repeated many times and are highly variable; used in DNA profiling.
33
What is a vector in genetics?
A vehicle used to transfer DNA sequences from one organism to another.
34
What is artificial selection?
The breeding of plants and animals to produce desirable traits in successive generations; also known as selective breeding
35
What is an autosomal trait?
A trait coded for by a gene on an autosome, a chromosome that is not a sex chromosome; a gene of this kind is called autosomal
36
What is codominance?
A state in which both alleles of a heterozygous individual are fully expressed in the phenotype
37
What is continuous variation?
Variation in a phenotype characteristic that shows a smooth range; this occurs when a trait is controlled by many genes; when graphed, such variation forms a bell-shaped (normal) curve
38
What is a dihybrid cross?
A cross between two organisms that are heterozygous at two gene loci
39
What is discontinuous variation?
Variation in a characteristic that shows two or just a few clearly distinct phenotypes
40
What is a dominant phenotype?
A phenotype that requires only one copy of its allele for it to be expressed in an individual
41
What is the first filial generation (F1)?
The first generation of offspring produced from a cross between two parents (P)
42
What is a gene?
A set of instructions that specifies the structure of a protein
43
What is a genotype?
The specific combination of alleles for a particular gene locus belonging to an individual or cell
44
What is heredity?
The study of inheritance; the genetic transmission of characteristics from one generation to the next
45
What does heterozygous mean?
A genotype with two different alleles for a single gene locus
46
What does homozygous mean?
A genotype with two identical alleles for a single gene locus
47
What is incomplete dominance?
The state in which a heterozygous individual has a phenotype that is intermediate between those of the corresponding homozygous individuals
48
What is independent assortment?
Random orientation of maternal and paternal homologous chromosomes at the equator during metaphase I, resulting in random combinations of alleles in the gametes at the conclusion of meiosis
49
What are linked genes?
Genes or alleles that are inherited together more frequently because they are located near one another on the same chromosome
50
What is a monohybrid?
An organism that is heterozygous with respect to a single gene
51
What is a monohybrid cross?
A cross between two monohybrids; only one gene is involved, and the cross is between two organisms that are heterozygous at one gene locus for a dominant and a recessive allele
52
What is a phenotype?
The actual form taken by a specific feature in a particular individual, based on their genotype and influenced by the environment
53
What is polygenic inheritance?
Transmission between generations of characteristics that are controlled by polygenes
54
What does pure-breeding mean?
A line of organisms that always produce offspring with the same phenotype when crossed with one another
55
What is a recessive phenotype?
A phenotype that requires two copies of its allele in an individual in order to be expressed
56
What is the second filial generation (F2)?
Offspring of the F1 generation; the second generation produced from a cross between two homozygous parents (P)
57
What is selective breeding?
A process by which humans domesticate animals or plants by purposely choosing individuals with the most desirable characteristics as parents for each successive generation of breeding
58
What is a test cross?
A technique used by geneticists in which an individual whose genotype is unknown for a dominant phenotype is crossed with an individual that is homozygous recessive at the locus in question
59
What is binary fission?
The division of a cell into two cells without mitosis; a prokaryotic cell undergoes binary fission to form two identical daughter cells; a form of asexual reproduction ## Footnote Binary fission is common in prokaryotes like bacteria.
60
Define bivalent.
A structure made up of two homologous chromosomes joined together, visible during prophase I of meiosis ## Footnote Bivalents are crucial for genetic recombination.
61
What is the cell cycle?
An ordered sequence of events in the life of a cell from when it was formed from a parent cell until its own division ## Footnote The cell cycle includes phases such as interphase and mitosis.
62
What is cell division?
The splitting of a cell into two new functioning cells ## Footnote Cell division can occur through mitosis or meiosis.
63
What is a cell plate?
The structure produced by dividing plant cells in the place where the new cell wall is forming ## Footnote The cell plate is crucial for cytokinesis in plant cells.
64
What is a centriole?
A minute rod-shaped organelle present in many resting cells that helps make the spindle fibres for cell division ## Footnote Centrioles are usually absent in plant cells.
65
Define centromere.
The waist-like constriction in a chromosome where the spindle fibres attach; it enables the movement of chromosomes during cell division ## Footnote Centromeres are essential for proper chromosome segregation.
66
What is a centrosome?
An organelle containing a pair of centrioles that duplicates during cell division and produces the spindle during cell mitosis and meiosis ## Footnote Centrosomes play a key role in organizing microtubules.
67
What is a chromatid?
Daughter strand of a duplicated chromosome that is joined to another chromatid by a centromere ## Footnote Chromatids are formed during the S phase of the cell cycle.
68
Define chromatin.
An organised, loosely coiled complex of DNA and its proteins found in eukaryotic non-dividing cells ## Footnote Chromatin condenses to form chromosomes during cell division.
69
What is a chromosome?
A structure composed of DNA and protein that contains linear arrays of genes carrying genetic information ## Footnote Eukaryotes have multiple linear chromosomes, while prokaryotes typically have one circular chromosome.
70
What is cleavage in cell biology?
The division of the cytoplasm in an animal cell ## Footnote Cleavage occurs during cytokinesis.
71
What is a cleavage furrow?
A shallow, ring-like depression that forms on the surface of an animal cell undergoing cytokinesis ## Footnote The cleavage furrow is defined by contractile microfilaments.
72
What is crossing over?
The exchange of genetic material between maternal and paternal homologous chromosomes during prophase I of meiosis ## Footnote Crossing over increases genetic diversity in gametes.
73
Define cytokinesis.
The division of the cytoplasm immediately after mitosis, meiosis I or meiosis II to create two separate daughter cells ## Footnote Cytokinesis is essential for the final separation of daughter cells.
74
What is differentiation?
The process during development whereby newly formed cells become more specialised as they mature ## Footnote An example is the development of root tip cells into phloem, xylem, and root hairs.
75
What does diploid (2n) mean?
Describes a cell or organism that has a genome containing two copies of each chromosome ## Footnote The diploid number is represented by 2n.
76
What is DNA?
The information-containing molecule present in all living things that contains the instructions for the production of proteins by the cell ## Footnote DNA is the genetic material that passes information to the next generation.
77
Define eukaryotic cell.
A complex cell containing membrane-bound organelles, including a nucleus ## Footnote Eukaryotic cells are more complex than prokaryotic cells.
78
What is fertilisation?
The fusion of haploid male and female gametes during sexual reproduction to produce a diploid zygote ## Footnote Random fertilisation contributes to genetic variability.
79
What is a gamete?
A male or female reproductive cell that combines at fertilisation ## Footnote In humans, gametes are ova and sperm cells.
80
Define gene.
A unit of heredity that transmits information from one generation to the next; a segment of DNA that codes for a polypeptide ## Footnote Genes are the basic units of inheritance.
81
What does genetic refer to?
The mechanisms and patterns of inheritance; relating to the transmission of coded chemical instructions ## Footnote Genetics studies how traits are passed from parents to offspring.
82
What is a genome?
All of the genetic material contained in an organism or a cell; includes chromosomes within the nucleus and DNA in mitochondria and chloroplasts ## Footnote The genome encompasses both nuclear and organellar DNA.
83
Define germline cell.
A specialised sex cell that gives rise to gametes; it specialises into male or female germ cells during embryonic development ## Footnote Germline cells are critical for reproduction.

12 Biology (9 decks)

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