3.4 Genetic information, variation and relationships between organisms - DNA, genes and chromosomes + DNA and protein synthesis Flashcards
1
Q
What is a gene?
A
A gene is a section of DNA that contains a code for making a polypeptide and functional RNA
2
Q
What determines the proteins of an organism?
A
Genes determine the proteins of an organism
3
Q
What is the definition of a locus?
A
The location of a particular gene on a chromosome
4
Q
What is an allele?
A
An allele is one of a number of alternative forms of a gene
5
Q
How many alleles do most genes occur in?
A
Most genes occur in two (an allelic pair), but occasionally in more different forms (multiple alleles)
6
Q
What is the structure of DNA in a eukaryotic cell nucleus?
A
DNA is stored as chromosomes
7
Q
How many pairs of chromosomes do humans have?
A
Humans have 23 pairs of chromosomes
8
Q
What is the total number of chromosomes in humans?
A
46 chromosomes in total
9
Q
Fill in the blank: The blue allele for flower color is an example of a _______.
A
allele
10
Q
Fill in the blank: The yellow allele for flower color is an example of a _______.
A
allele
11
Q
What is an exon?
A
An exon is a coding region of a gene that is expressed
12
Q
A
13
Q
What are pairs of matching chromosomes called?
A
Homologous pairs
Homologous pairs consist of two copies of the same chromosome.
14
Q
What is a homologous pair of chromosomes characterized by?
A
Same size and same genes, but different alleles
Alleles are different versions of a gene.
15
Q
How many homologous pairs do humans have?
A
23 homologous pairs
16
Q
Where is DNA stored in eukaryotic cells?
A
Inside the nucleus
Eukaryotic cells have a defined nucleus that contains the cell’s genetic material.
17
Q
What shape are chromosomes in eukaryotic cells?
A
Linear
18
Q
What are chromosomes made of?
A
DNA tightly coiled and wrapped around histones
Histones are proteins that help package DNA into a compact form.
19
Q
What is the function of histones in chromosomes?
A
To create the chromosome by wrapping DNA around them
20
Q
What is the role of the centromere in a chromosome?
A
To hold sister chromatids together
21
Q
Fill in the blank: DNA is stored as _______ inside the nucleus.
A
chromosomes
22
Q
What term describes the ends of chromosomes?
A
Telomere
23
Q
Define ‘chromosome’.
A
A structure that contains DNA and is found in the nucleus of eukaryotic cells
24
Q
What are nucleosomes?
A
Units of DNA coiled around histones
Nucleosomes are the fundamental units of chromatin.
25
What is the relationship between chromatids and chromosomes?
Chromatids are the two identical halves of a replicated chromosome
26
True or False: Homologous chromosomes can have different alleles.
True
27
What is the shape of DNA molecules in prokaryotes?
Short and circular
28
Is prokaryotic DNA wound around histones?
No, it supercoils to fit in the cell
29
What type of cells contain additional DNA in mitochondria and chloroplasts?
Eukaryotic cells
30
What is mitochondrial DNA similar to?
Prokaryotic DNA
31
Fill in the blank: Prokaryotes carry DNA that is _______.
short and circular
32
What is a key characteristic of prokaryotic DNA?
It is not wound around histones
33
True or False: Mitochondrial DNA is long and linear.
False
34
What do mitochondria and chloroplasts have in common regarding DNA?
Both contain short and circular DNA
35
What cellular structure is associated with supercoiling of DNA?
Prokaryotic cells
36
What type of organism's DNA is characterized by supercoiling?
Prokaryotes
37
Fill in the blank: The DNA in mitochondria is _______ to prokaryotic DNA.
similar
38
What is the relationship between the structure of prokaryotic DNA and cell size?
It supercoils to fit in the cell
39
List two organelles that contain their own DNA.
* Mitochondria
* Chloroplast
40
What is a Start Codon?
A sequence of three bases at the start of every gene that helps to initiate translation.
## Footnote
Start codons are essential for the translation process in protein synthesis.
41
What is a Stop Codon?
A sequence of three bases at the end of a gene that does not code for an amino acid and marks the end of a polypeptide chain.
## Footnote
Stop codons cause ribosomes to detach, stopping the translation process.
42
What does the term 'triplet code' refer to?
A sequence of three DNA bases that codes for an amino acid.
## Footnote
Each triplet, or codon, corresponds to a specific amino acid during protein synthesis.
43
List the three key features of the genetic code.
* Degenerate
* Universal
* Non-overlapping
## Footnote
These features highlight the complexity and efficiency of the genetic code in coding for amino acids.
44
What does 'degenerate' mean in the context of the genetic code?
Each amino acid is coded for by more than one triplet of bases, allowing for multiple codons to specify the same amino acid.
## Footnote
For example, tyrosine can be coded by ATA and ATG.
45
How many possible triplet combinations are there in the genetic code?
64 possible triplet combinations (4x4x4).
## Footnote
This is due to the four bases (A, T, C, G) and the three-base coding system.
46
True or False: A point mutation always results in a different amino acid being coded.
False
## Footnote
Due to the degeneracy of the genetic code, a point mutation may still code for the same amino acid, having no effect.
47
What does the genetic code being described as universal mean?
The same triplet of bases codes for the same amino acid in all organisms.
48
What is the advantage of the genetic code being universal?
It allows for genetic engineering, such as inserting the human gene for insulin into bacteria.
49
Define non-overlapping in the context of genetic coding.
Each base in a gene is only part of one triplet of bases that codes for one amino acid.
50
What is a codon?
A triplet of bases that is read as a discrete unit coding for one amino acid.
51
What is the effect of a point mutation in a non-overlapping genetic code?
It will only affect one codon and therefore one amino acid.
52
What are introns?
Sections of DNA that do not code for amino acids and are found in eukaryotic DNA.
53
What happens to introns during mRNA processing?
They get removed (spliced) out of mRNA molecules.
54
What are exons?
Sections of DNA that do code for amino acids.
55
True or False: Introns are found in prokaryotic DNA.
False.
56
Fill in the blank: ________ are the sections of DNA that code for amino acids.
Exons
57
Fill in the blank: ________ are sections of DNA that do not code for amino acids.
Introns
58
What is the genome?
The complete set of genes in a cell
59
What is the proteome?
The full range of proteins that a cell is able to produce
60
How many DNA base pairs do bacteria typically contain?
On average 600,000 DNA base pairs
61
How many DNA base pairs do humans typically contain?
3 billion DNA base pairs
62
What are genes?
Sections of DNA that contain a code for polypeptide and functional RNA
63
What is an allele?
One of a number of alternative forms of a gene
64
How many pairs of chromosomes do humans have?
25 pairs of chromosomes
65
What are homologous pairs of chromosomes?
Chromosomes that are the same size and have exactly the same genes
66
Where is DNA found besides the nucleus?
In chloroplasts and mitochondria
67
What is a characteristic of mitochondrial and chloroplast DNA?
It is short and circular
68
What are the features of the genetic code?
Degenerate, universal, and non-overlapping
69
True or False: The genetic code being degenerate reduces the chances that a point mutation will change the shape of a protein.
True
70
Fill in the blank: The genetic code has three features: ______, universal, and non-overlapping.
degenerate
71
What links genes and alleles to inheritance?
Topic 7
72
What links DNA and genes to gene technologies?
Isolating DNA fragments and cloning
73
What links the presence of DNA in mitochondria and chloroplasts to cellular processes?
Respiration and photosynthesis
74
What is mRNA?
A copy of a gene from DNA created in the nucleus
## Footnote
mRNA carries the genetic code of one gene to a ribosome in the cytoplasm
75
Why can't DNA leave the nucleus?
DNA is too large and would risk damage from enzymes
## Footnote
Damage to DNA would destroy the genetic code permanently
76
What is the structure of mRNA?
Single-stranded and shorter than DNA
## Footnote
mRNA is only the length of one gene
77
What is a codon?
Every 3 bases in the mRNA sequence that code for a specific amino acid
## Footnote
Codons are crucial for protein synthesis
78
What is the role of tRNA?
To attach to amino acids and transfer them to the ribosome
## Footnote
tRNA creates the polypeptide chain
79
Describe the shape of tRNA.
Single-stranded but folded into a cloverleaf shape
## Footnote
This shape is stabilized by hydrogen bonds
80
What determines the specific amino acid attached to tRNA?
The 3 bases on tRNA that are complementary to mRNA codons
## Footnote
These complementary bases are known as the anticodon
81
Fill in the blank: mRNA is created in the _______.
nucleus
82
Fill in the blank: The three bases on mRNA are called _______.
codons
83
True or False: tRNA is found only in the nucleus.
False
84
What holds the cloverleaf shape of tRNA in place?
Hydrogen bonds
85
What are the bases on tRNA that pair with mRNA called?
Anticodon
86
What is the function of RNA polymerase?
To synthesize mRNA from a DNA template
## Footnote
RNA polymerase plays a crucial role in transcription
87
What is the result of transcription in prokaryotic organisms?
The production of a finished mRNA molecule that requires no modification.
88
Why does prokaryotic DNA not require modification of mRNA?
Because prokaryotic DNA does not contain any introns.
89
What is pre-mRNA in eukaryotes?
The mRNA that is made following transcription in eukaryotes which still contains introns.
90
What must happen to pre-mRNA before it can participate in translation?
It must be modified to remove introns and become mature mRNA.
91
What is the role of a spliceosome?
To splice out introns from pre-mRNA.
92
What are exons?
The coding regions of mRNA that remain after introns are removed.
93
Fill in the blank: In eukaryotes, introns are spliced out by _______.
[spliceosome]
94
True or False: Eukaryotic DNA contains both introns and exons.
True.
95
What happens to the mRNA after introns are removed in eukaryotes?
It becomes mature mRNA ready to leave the nucleus.
96
What is the primary difference in mRNA processing between prokaryotes and eukaryotes?
Prokaryotes produce finished mRNA directly, while eukaryotes produce pre-mRNA that requires modification.
97
What is a polypeptide chain?
A sequence of amino acids linked by peptide bonds.
98
What does ATIP stand for?
Adenosine triphosphate.
99
Define codon.
A sequence of three nucleotides in mRNA that codes for a specific amino acid.
100
What is the role of tRNA?
To transport amino acids to the ribosome during translation.
101
What is an anticodon?
A sequence of three nucleotides in tRNA that is complementary to a codon in mRNA.
102
What is translation in the context of protein synthesis?
The process of creating a polypeptide chain using the mRNA base sequence and tRNA.
103
Where does translation take place?
In the cytoplasm at the ribosome.
104
What initiates the attachment of the ribosome during translation?
The start codon on the mRNA.
105
What aligns opposite the mRNA at the ribosome?
The tRNA molecule with the complementary anticodon.
106
What happens to the ribosome as it moves along the mRNA?
It enables another complementary tRNA molecule to attach to the next codon.
107
How are two amino acids joined during translation?
By a peptide bond, catalyzed by an enzyme and requiring ATP.
108
What signifies the end of translation?
The ribosome reaching the stop codon.
109
What occurs to the polypeptide chain after it is created?
It enters the Golgi body for folding and modification.
110
Fill in the blank: The stop codon _______ for an amino acid.
does not code
111
What is the first stage of protein synthesis?
Transcription
## Footnote
Transcription occurs in the nucleus and involves copying a gene from DNA into mRNA.
112
What is the second stage of protein synthesis?
Translation
## Footnote
Translation occurs in the cytoplasm and involves forming a polypeptide chain.
113
Where does transcription occur?
In the nucleus
## Footnote
This is where the DNA is located and is copied into mRNA.
114
What enzymes are involved in transcription?
* DNA helicase
* RNA polymerase
## Footnote
These enzymes help unwind the DNA and synthesize the mRNA strand.
115
What is the role of ribosomes in protein synthesis?
They facilitate translation
## Footnote
Ribosomes provide a site for mRNA and tRNA to interact during protein synthesis.
116
What do tRNA molecules bring to the ribosome during translation?
Specific amino acids
## Footnote
Each tRNA carries an amino acid that corresponds to the codon on the mRNA.
117
What are anticodons?
Sequences on tRNA that are complementary to mRNA codons
## Footnote
Anticodons ensure the correct amino acid is added to the growing polypeptide chain.
118
What is the relationship between protein synthesis and mutations?
Mutations can change the DNA base sequence
## Footnote
This can result in the creation of a different polypeptide chain.
119
What molecule is required for translation and links to biological energy usage?
ATP
## Footnote
ATP is used during translation for energy to facilitate the process.
120
How is protein synthesis linked to gene technology?
It enables genetic engineering
## Footnote
For example, bacteria can be engineered to synthesize human insulin.
121
Fill in the blank: Protein synthesis is a two-stage process involving _______ and translation.
Transcription
122
True or False: Translation occurs in the nucleus.
False
## Footnote
Translation occurs in the cytoplasm.
123
What is formed during translation?
A polypeptide chain
## Footnote
This chain is composed of amino acids linked together.
