Lect 19 Flashcards
(147 cards)
1
Q
What is genetics?
A
The study of inheritance and variation
- The basis of inheritance
- The mechanism of evolution
- A methodology for experimental biology
- An essential tool for all Biological and Medical Scientists
2
Q
What are the four key roles of genetics?
A
- The basis of inheritance
- The mechanism of evolution
- A methodology for experimental biology
- An essential tool for all Biological and Medical Scientists
3
Q
True or False: Genetics is not important for Biological and Medical Scientists.
A
False
Genetics is considered an essential tool for professionals in these fields.
4
Q
Fill in the blank: Genetics is the basis of _______.
A
inheritance
This foundational role of genetics is crucial for understanding how traits are passed down.
5
Q
What methodology does genetics provide?
A
A methodology for experimental biology
This methodology allows scientists to conduct experiments and research in various biological contexts.
6
Q
What mechanism does genetics explain?
A
The mechanism of evolution
Understanding genetics helps to explain how species adapt and evolve over time.
7
Q
What are somatic cells?
A
Any body cells that do not produce gametes (egg or sperm cells).
Somatic cells make up most of the body’s tissues and organs.
8
Q
What are germ cells?
A
A diploid reproductive cell that gives rise to a gamete.
Germ cells are essential for sexual reproduction.
9
Q
Define diploid.
A
Cells with 2 sets of chromosomes.
Diploid cells contain two copies of each chromosome, one from each parent.
10
Q
Define haploid.
A
Cells with one set of chromosomes.
Haploid cells are produced during meiosis and are found in gametes.
11
Q
What does diploid mean in terms of genetic complement?
A
2 copies of the basic genetic complement for that organism.
This refers to the total number of chromosomes present in diploid cells.
12
Q
What does haploid mean in terms of genetic complement?
A
1 copy of the basic genetic complement for that organism.
Haploid cells contain half the number of chromosomes compared to diploid cells.
13
Q
What do children inherit from their parents?
A
Genes
14
Q
What are phenotypes created from?
A
Complex interactions of genes
Phenotypes refer to the observable characteristics of an organism.
15
Q
What are genes made up of?
A
Segments of DNA
Genes are the units of heredity
16
Q
Where are genes located?
A
On a particular location called a locus on a chromosome
17
Q
How are genes passed on to the next generation?
A
Through reproductive cells called gametes (sperm and egg)
18
Q
What is the purpose of the cytogenetic location description?
A
To describe the position of a particular band on a stained chromosome
19
Q
What do the letters P and q represent in cytogenetic location?
A
P is the short arm, q is the long arm
20
Q
What does the location description like 7q31.2 imply?
A
It relates to the region and bands on a chromosome
21
Q
What is the significance of the tags like BN7_0030?
A
They are identifiers assigned to genes
22
Q
What is the role of colchicine in cytogenetics?
A
It is a tubulin inhibitor used in metaphase banding
23
Q
What does the banding in metaphase relate to?
A
Areas of GC and AT rich sections
24
Q
What are chromatin domains?
A
Regions shown during metaphase banding
25
What is the length of the human genome?
3x10^9 base pairs
## Footnote
The length of each base pair is 0.34nm, resulting in a total length of approximately 1.02 meters.
26
What is the length of DNA in the nucleus of a human sperm cell?
Packaged into 2-3µm long
## Footnote
The sperm nucleus contains the compacted DNA structure.
27
What role do Histones play in relation to DNA?
Histones help with the folding of DNA.
28
How is DNA structured around Histones?
DNA is wrapped around Histones, then looped and coiled.
29
What is the effect of Methylation on DNA?
Methylation affects how tightly coiled the DNA is and switches genes off.
30
What do the band and colors seen on chromosomes represent?
Different areas of DNA that are more tightly packed than others.
31
Why do certain areas of DNA stain differently?
They stain differently due to their varying degrees of tight packing.
32
What processes occur at the correct place and time regarding DNA?
DNA gets replicated and transcribed at the correct place and time
33
Fill in the blank: Proteins called _______ help with the folding of DNA.
[Histones]
34
True or False: Methylation can make DNA more loosely coiled.
False
35
What are discrete lengths of DNA called?
Chromosomes
## Footnote
Chromosomes carry genetic information.
36
How many chromosomes do humans have?
23
## Footnote
This includes 22 pairs of autosomes and one pair of sex chromosomes.
37
Does the complexity of an organism reflect the number of chromosomes it has?
No
## Footnote
Organism complexity does not correlate with chromosome number.
38
What is the process of Mitosis?
A normal cell life cycle that involves replacing cells that are removed or damaged
## Footnote
Mitosis is essential for growth and repair in organisms.
39
What are the two types of cell division?
* Mitosis
* Meiosis
## Footnote
Mitosis is for normal cell life cycles, while meiosis is specifically for reproduction.
40
True or False: Mitosis is used for reproduction.
False
## Footnote
Mitosis is part of the normal cell life cycle, while meiosis is the process used for reproduction.
41
Fill in the blank: _______ is the type of cell division for reproduction.
Meiosis
## Footnote
Meiosis results in the formation of gametes, such as sperm and eggs.
42
label the diagram:
43
What structure contains a pair of centrioles during prophase?
Centrosome
## Footnote
The centrosome is crucial for organizing microtubules.
44
What happens to the centrioles as mitosis progresses?
They move to opposite poles of the cell
## Footnote
This movement is essential for spindle apparatus formation.
45
What is the role of centrioles in mitosis?
They help organize the microtubules that form the spindle apparatus
## Footnote
Proper organization is vital for chromosome segregation.
46
What state do chromosomes begin in before prophase?
Unfolded (chromatin) state
## Footnote
This state allows for the condensation necessary for mitosis.
47
What is the significance of chromosome condensation during prophase?
It ensures that chromosomes can be properly segregated without damage
## Footnote
Proper condensation is critical for mitosis.
48
What occurs during prometaphase regarding the nuclear envelope?
It breaks down
## Footnote
This allows spindle microtubules to access the chromosomes.
49
What attaches to the kinetochores during prometaphase?
Spindle microtubules
## Footnote
Kinetochores are located at the centromere of each chromosome.
50
What is the function of kinetochores?
They ensure that microtubules bind at the correct location for accurate chromosome movement
## Footnote
This is essential for proper chromosome segregation.
51
What is the state of chromosomes during metaphase?
Most condensed and shortest state
## Footnote
This facilitates their alignment at the metaphase plate.
52
Where do chromosomes align during metaphase?
At the metaphase plate
## Footnote
The metaphase plate is an imaginary plane in the middle of the cell.
53
What attaches to the kinetochores during metaphase?
Spindle fibers from both poles
## Footnote
This attachment is crucial for the separation of sister chromatids.
54
What happens during anaphase?
Sister chromatids are separated and pulled toward opposite poles
## Footnote
This ensures each daughter cell receives an identical set of chromosomes.
55
What must occur before mitosis can start?
DNA replication must be complete
## Footnote
This is a prerequisite for ensuring accurate chromosome segregation during mitosis.
56
What are the sex chromosomes in humans?
X and Y
57
What chromosome pair do human females have?
XX
58
What chromosome pair do human males have?
XY
59
Which chromosome is larger in size, X or Y?
X
60
What does a new individual inherit from the mother at fertilisation?
an X chromosome
61
What does a new individual inherit from the father at fertilisation?
an X or a Y chromosome
62
What combination of chromosomes results in a male?
Inheriting an X and a Y
63
What combination of chromosomes results in a female?
Inheriting an X and an X
64
What are the chromosomes that do not determine sex called?
autosomes
65
How many pairs of autosomes do humans have?
22 pairs
66
What are the chromosomes in each pair called?
Homologous chromosomes or homologs
67
What characteristics do chromosomes in a homologous pair share?
They are the same length and carry alleles of the same genes
68
What are sister chromatids?
Complete duplication of each other
69
What are non-sister chromatids?
Same genes or alleles on different chromosomes
70
What is a human karyotype?
An ordered display of the pairs of chromosomes in a cell
71
What is a centromere?
A region where kinetochores group of proteins interact
72
What are the two identical halves of a replicated chromosome called?
Sister chromatids
73
What are the chromatids in a homologous pair that are not identical called?
Nonsister chromatids
74
What constitutes a pair of homologous chromosomes?
One chromosome from each parent
75
Fill in the blank: A homologous pair consists of one chromosome from each _______.
[parent]
76
What is the composition of each pair of homologous chromosomes?
Each pair includes one chromosome from each parent
## Footnote
This means one chromosome is inherited from the mother and one from the father.
77
How many chromosomes are present in a somatic cell?
46 chromosomes
## Footnote
This is made up of two sets of 23 chromosomes.
78
What is a diploid cell?
A cell that has two sets of chromosomes
## Footnote
In humans, diploid cells are represented as 2n.
79
What is the diploid number for humans?
46 (2n = 46)
## Footnote
This indicates that humans have 46 chromosomes in their diploid cells.
80
What is Meiosis?
Cell division producing gametes each possessing the haploid number of chromosomes (n) and haploid content of DNA (c).
## Footnote
Meiosis is essential for sexual reproduction.
81
What happens during reductional division in meiosis?
The number of chromosomes is reduced. After the first reductional division, there are 1n and 2c.
## Footnote
2C represents duplicated content of DNA.
82
What does 2C signify in meiosis?
Duplicated content of DNA.
## Footnote
This indicates that there are two copies of each chromosome before the second division.
83
Why is meiosis necessary?
It is required to allow offspring to be produced with half of their genetic information from their mother and half from their father.
## Footnote
This process ensures genetic diversity in offspring.
84
Fill in the blank: Meiosis produces gametes with a _______ number of chromosomes.
haploid
## Footnote
The haploid number is represented as 'n'.
85
True or False: Meiosis results in cells with a diploid number of chromosomes.
False
## Footnote
Meiosis results in haploid cells, each with half the chromosome number.
86
What is the main purpose of mitosis?
To produce new cells which contain a diploid set of chromosomes.
87
When does mitosis occur in the cell cycle?
Before cytokinesis after G.
88
Where does mitosis take place?
In many tissues that need to replace cells, e.g., blood, the epithelium of the small intestine.
89
What are the phases of mitosis?
* Prophase
* Prometaphase
* Metaphase
* Anaphase
* Telophase
90
True or False: Mitosis occurs only in tissues that do not require cell replacement.
False
91
Fill in the blank: Mitosis is necessary to replace cells that have _______.
died or been removed.
92
What phase of the cell cycle does Meiosis begin?
After S-phase
93
What is the diploid number of chromosomes represented as?
2n
94
What does '4c' represent in the context of Meiosis?
4x the haploid content of DNA
95
True or False: Meiosis begins before the DNA has been replicated.
False
96
What is the outcome of meiosis in terms of daughter cells?
Results in four daughter cells
## Footnote
Unlike mitosis, which results in two daughter cells.
97
How does the chromosome number in daughter cells compare to the parent cell in meiosis?
Each resulting daughter cell has half the number of chromosomes as the parent cell.
98
What are the two sets of cell divisions in meiosis called?
Meiosis I and Meiosis II.
99
What happens to homologous chromosomes during Meiosis I?
Homologous chromosomes separate.
100
What occurs during Meiosis II?
Sister chromatids separate.
101
What type of cells are formed after Meiosis I?
Haploid cells with duplicated chromosomes.
102
What type of cells are formed after Meiosis II?
Haploid cells with unduplicated chromosomes.
103
What precedes meiosis, similar to mitosis?
The replication of chromosomes.
104
What are sister chromatids?
Duplicated chromosomes in a diploid cell.
105
What process occurs in meiosis 1 involving homologous chromosomes?
Homologous chromosomes line up beside one another by synapse
106
What is the result of the synapsis of homologous chromosomes in meiosis 1?
It allows them to match their genes
107
What happens to homologous chromosomes after they line up during meiosis 1?
They are split into haploid cells with duplicated chromosomes
108
What process forms 2 haploid daughter cells?
Reductional Division
## Footnote
This process is crucial in meiosis, where the chromosome number is halved.
109
What type of cells are formed from diploid cells?
Haploid daughter cells
## Footnote
Haploid cells contain half the number of chromosomes compared to diploid cells.
110
Fill in the blank: Reductional Division results in _______ daughter cells.
haploid
111
What does mitosis do to the number of chromosome sets?
Mitosis conserves the number of chromosome sets, producing cells that are genetically identical to the parent cell.
## Footnote
Mitosis results in two diploid daughter cells from one diploid parent cell.
112
What is the outcome of meiosis in terms of chromosome sets?
Meiosis reduces the number of chromosome sets from two (diploid) to one (haploid).
## Footnote
This process results in four genetically different haploid cells.
113
How do the cells produced by meiosis compare to the parent cell?
The cells produced by meiosis are genetically different from the parent cell and from each other.
## Footnote
This genetic variation is crucial for evolution and diversity in sexually reproducing populations.
114
What is similar about the mechanism for separating sister chromatids in meiosis and mitosis?
The mechanism for separating sister chromatids is virtually identical in Meiosis II and Mitosis.
## Footnote
Both processes involve the spindle apparatus and similar phases of cell division.
115
What are the three unique events that occur in Meiosis I?
1. Paired homologous chromosomes (tetrads) at the metaphase plate instead of individual replicated chromosomes.
2. Separation of homologous chromosomes instead of sister chromatids.
3. Synapsis and crossing over where homologous chromosomes connect and exchange genetic information.
## Footnote
The process of crossing over involves many proteins.
116
What type of chromosomes are at the metaphase plate during Meiosis I?
Paired homologous chromosomes (tetrads).
## Footnote
This is different from mitosis where individual replicated chromosomes are present.
117
What is synapsis in the context of meiosis?
The physical connection of homologous chromosomes.
## Footnote
This process is essential for genetic recombination.
118
What occurs during crossing over?
Homologous chromosomes exchange genetic information.
## Footnote
This process increases genetic diversity and involves many proteins.
119
What is the original source of genetic diversity?
Mutations
## Footnote
Mutations are changes to an organism's DNA.
120
What do mutations create that contributes to genetic variation?
Alleles
## Footnote
Alleles are different versions of genes.
121
What process reshuffles alleles to produce genetic variation?
Meiosis and reproduction
## Footnote
This process occurs during sexual reproduction.
122
What is independent assortment of chromosomes?
Equal chance of chromosomes from each parent lining up at metaphase I
## Footnote
This process contributes to genetic variation during meiosis.
123
What is crossing over?
Results in recombinant chromosomes that contain genes from each parent
## Footnote
This occurs during prophase I of meiosis and enhances genetic diversity.
124
What role does random fertilization play in genetic variation?
Any egg with any sperm can combine
## Footnote
This adds to the genetic diversity of the offspring.
125
Fill in the blank: __________ results in recombinant chromosomes that contain genes from each parent.
Crossing over
126
True or False: Independent assortment of chromosomes occurs during metaphase II.
False
## Footnote
Independent assortment occurs during metaphase I.
127
What is independent assortment of chromosomes?
Independent assortment refers to the random orientation of homologous pairs of chromosomes at metaphase I of meiosis.
128
During which phase of meiosis does independent assortment occur?
Independent assortment occurs during metaphase I of meiosis.
129
What does independent assortment allow for in daughter cells?
Independent assortment allows each pair of chromosomes to sort maternal and paternal homologues into daughter cells independently of other pairs.
130
What is the formula for the number of combinations possible when chromosomes assort independently into gametes?
2^n (where n is the haploid number)
## Footnote
This formula represents the independent assortment of chromosomes during gamete formation.
131
How many possible combinations of chromosomes are there for humans?
More than 8.4 million (2^23)
## Footnote
This value reflects the genetic diversity resulting from independent assortment.
132
What is crossing over in meiosis?
A process that can lead to genetic variation by producing recombinant chromosomes. Crossing over begins very early in prophase I as homologous chromosomes pair up gene by gene.
133
What do recombinant chromosomes combine?
Genes inherited from each parent.
134
True or False: Crossing over does not affect genetic variation.
False
135
Fill in the blank: Crossing over in meiosis produces _______.
[recombinant chromosomes]
136
Describe the process of crossing over
137
What is random fertilization?
Any sperm can fuse with any ovum (unfertilized egg)
## Footnote
This process contributes to genetic diversity in offspring.
138
How many possible chromosome combinations does each gamete have?
8.4 million
139
What is the total number of diploid combinations possible from the fusion of two gametes?
About 70 trillion
## Footnote
The fusion of two gametes, each with a possible 8.4 million possible chromosome combinations produces a zygote with about 70 trillion diploid combinations.
140
What drives evolution?
Genetic variation
141
Fill in the blank: _______ variation drives evolution.
Genetic variation
142
Describe all the processes that lead to genetic variations
1. Reshuffling of alleles during sexual reproduction produces genetic variation.
2. Further variation is introduced as each homologous pair can line up independently during metaphase I - Independent assortment of chromosomes.
3. More variation occurs via crossing over of sister chromatids and breaking and re-joining at the crossover point the chiasma.
4. Natural selection results in the accumulation of genetic variations favoured by the environment.
143
What is epigenetics?
The study of the chemical modification of specific genes or gene-associated proteins of an organism
## Footnote
Epigenetics examines how these modifications affect gene expression and organism development.
144
What happens as an organism grows and develops in terms of chemical reactions?
As an organism grows and develops, chemical reactions activate and deactivate parts of the genome at strategic times and in specific locations.
145
What are epigenetic tags?
Chemical modifications that influence gene transcription levels
## Footnote
Methylation is a common type of epigenetic tag.
146
What is methylation in the context of epigenetics?
An epigenetic tag that influences the level of transcription of particular genes
## Footnote
Methylation can either activate or silence gene expression.
147
How are epigenetic tags maintained during cell division?
They are faithfully reproduced as cells grow and divide
## Footnote
This ensures that epigenetic information is passed on to daughter cells.
