Lectures 3 and 4 Flashcards
1
Q
What are the two main factors that can cause hearing loss to occur?
A
Environmental factors and genetic
2
Q
What is an example of an environmental factor that can cause hearing loss?
A
Viral infection that is acquired during pregnancy
CMV, meningitis
3
Q
Why are hearing losses genetic?
A
The development of the auditory-vestibular system depends on sequential activation of multiple genes
Problems with one gene can cause hearing loss
4
Q
Can hearing loss be both genetic and environmental?
A
Yes
Could have a genetic mutation that makes you susceptible to hearing loss that only presents itself after taking a certain type of medication
5
Q
Why is understanding genetic causes of hearing loss important?
A
It could allow doctors to inform families about their chances of having children with hearing loss
It could also predict if their hearing loss is going to get worse
6
Q
What does syndromic mean?
A
They don’t just have hearing loss, they also have problems with other organ systems
7
Q
Is it common for children to have genetic deafness/hearing loss even if neither of one of their parents are affected?
A
Yes
This is why genetic testing for hearing loss is important
8
Q
What is a cell?
A
The basic unit of structure and function in all organisms
9
Q
What are genes?
A
They control the shape, size, and function of cells
10
Q
What are the two main cell types?
A
Prokaryotic and eukaryotic
11
Q
What are prokaryotic cells?
A
Cells with a plasma membrane but do not have a membrane-bound nucleus or other membrane bound organelles
DNA found floating in the cytoplasm
Unicellular
12
Q
What are eukaryotic cells?
A
Human cells
Plasma membrane and nuclear membrane along with other organelles
Nucleus has DNA
13
Q
What is a nuclear membrane?
A
The cell wall or covering around the nucleus
14
Q
What are somatic cells?
A
Body cells
Everything but sex cells
Cells that differentiate into tissues and organs in the body
15
Q
What are germ cells?
A
Egg and sperm cells
Sex cells
Cells from which a new organism can develop
16
Q
T/F: Your cells work together
A
True
17
Q
Can different issues in the body (cardiovascular) affect the ears?
A
Yes
Everything is interrelated
18
Q
How are all cells similar?
A
They all have the same molecular building blocks
They all have similar methods for storage
They all have similar cell maintenance methods
They all have similar methods for expression of genetic information
They all have similar processes of energy metabolism
They all have similar methods for molecular transport and cell signaling
They all have similar processes for cell development and structure
19
Q
What is cell signaling?
A
How cells communicate with each other and their environments
20
Q
What are the ways that cells can signal to each other?
A
They can do so through direct contact or by the release of substances (hormones or NT)
21
Q
What is MS?
A
When myelin degenerated and cell signaling is affected
22
Q
What is a plasma membrane?
A
The cell wall
Dynamic and active component of the cell
23
Q
What does the plasma membrane do?
A
It prevents the free flow of molecules in and out of the cell
24
Q
T/F: Eukaryotic cells also have extensive internal membranes that further subdivide the cell into compartments that contain the organelles
A
True
25
What is the plasma membrane comprised of?
A bilayer of phospholipid molecules
Two hydrophobic fatty acid tails and a hydrophilic head
26
What does the phosphate group form on in the bilayer?
The water loving head
27
What is a phospholipid?
A lipid containing a phosphate group
Smaller amounts of other lipids such as cholesterol are inserted into the phospholipid framework
28
What are phospholipid membrane impermeable to?
Water
All ions
All hydrophilic small molecules
29
Does the plasma membrane also have proteins?
Yes
These proteins allow specific ions and small molecules to cross through
Other give the cell its shape or allow the shape to change
30
T/F: the molecules on the plasma membrane provide cells with their molecular identity
Yes
31
The type and number of molecules are genetically controlled and responsible for what important cell properties?
Blood types
Determination of compatibility in organ transplants
32
T/F: Some genetic disorders (cystic fibrosis) are associated with plasma membrane anomalies
True
33
What is cytoplasm?
A complex mixture of molecules and structural components
34
What is a cytoskeleton?
Within cytoplasm
A system a microfilaments and microtubules that provide the cell with strength and rigidity
Helps anchor cellular structures
Helps organize cell
Key role in cell motility
35
Are microtubules and microfilaments protein?
Yes
36
What are microfilaments mostly comprised of?
Actin (for contraction)
Tiny hair-like
37
Do eukaryotic or prokaryotic cells have extensive internal membranes that enclose specific compartments and make to organelles?
Eukaryotic
38
What do internal membranes do?
Define the organelles
Control their ionic composition so that it is different from the cytoplasm and other organelles
39
Does each organelle have a unique set of proteins that enables it to carry out its function?
Yes
40
Is everything that is functional in the body made up of proteins?
Yes
41
What is the endoplasmic reticulum?
An organelle
Network of membranes that export protein from cells
42
What are the two types of endoplasmic reticulum?
Smooth - lacks ribosomes, lipid synthesis (function)
Rough - ribosomes, synthesize and process proteins (function)
43
What are ribosomes?
Small particles found both in the endoplasmic reticulum and free in the cytoplasm
Made up of (ribonucleic acid) RNA and protein
Ribosomes link amino acids together in the order specified by messenger RNA (mRNA) molecules
44
What are amino acids?
The building blocks of protein
45
What is the golgi apparatus?
Flattened membrane sacs that receive proteins from the ER
Proteins are further processed here before being forwarded to their final destination
46
What are lysosomes?
Membrane-enclosed sacs that contain digestive enzymes
They break down or recycle worn-out and obsolete cells parts
47
Mitochondria
48
49
What is the nucleus?
The largest, most prominent of the organelles
Responsible for growth and reproduction of the cell
Enclosed with a double membrane that allows direct communication between the nucleus and cytoplasm
Contains the cell’s genetic information (DNA) organized into genes that determines the shape, structure, and range of functions carried out by the cell
50
T/F: There are dense regions within the nucleus called nucleoli that synthesize ribosomes
True
51
T/F: Darks strands and clumps of chromatin (chromosomes) are seen throughout the nucleus
True
52
What is chromatin?
The complex of DNA and proteins that make up a chromosome
Chromatin is organized into chromosomes
53
What are chromosomes?
Rod-shaped microscopic structures carrying the genes that carry genetic information transmitted from generation to generation
As the cell prepares to divide, the chromatin condenses and coils to form chromosomes
54
How are chromosomes formed?
They take the form of two chromatids connected at the centromere to create an "X" shape
Two chromatids joined by the centromere are called sister chromatids
55
How many pairs of chromosomes are in humans?
23 pairs (46 chromosomes)
56
What are the short and long arms of the chromosome called?
The short arm is p and the long arm is q
57
How many pairs of chromosomes are autosomes?
22
1 pair is sex chromosomes
58
Is the Y chromosome in males super short?
Yes
59
What is a ploidy?
It is a number
A number of sets of chromosomes in a cell
60
What is a diploid?
Each chromosome is represented twice as a member of a homologous pair, one set from each parent
61
What is a haploid?
One full set of chromosomes occurring in a mature germ cell or half the number of chromosomes (23) found in a normal somatic cell (22X or 22Y)
62
What is a karyotype?
The general appearance of somatic chromosomes
63
What is a homologous pair?
An identical pair (one set from each parent)
64
What is a genotype?
Describes alleles present in a gene
The genetic composition of an individual, i.e., the fundamental characteristic of an organism in terms of hereditary factors
65
What is a phenotype?
Describes the expression of an allele combination present in a gene
The manifest characteristics of an organism collectively, i.e., traits that result from both its hereditary and its environment – nature and nurture
66
What do many cells in the body alternate between?
Division and non-division
67
How long is cell division?
Could vary from minutes to years
68
What is the cell cycle?
The sequence of events from one division to another
69
What is the purpose of dividing?
To grow and to replace old cells
Cells have shelf-lives
70
What never divides?
Hair cells and nerve cells
71
What are the three phases of the cell cycle?
Interphase
Mitosis
Cytokinesis
72
Can some cells pass though the cell cycle continuously?
Yes, such as red blood cells
73
What does a cell do when it is not continuously dividing?
Enters a resting or G0 phase
74
Can a resting phase be temporary?
Yes most cells will reenter the cell cycle if conditions change (damage)
Other cells, like hair cells, will never reenter the cell cycle
75
T/F: When the cells escape from control of the cycle they become cancerous
True
Cancer is comprised of your own rebellious cells
Divide faster than normal cells
Chemo kills cancer cells but also normal cells too
76
What is interphase?
The time between cell divisions
Period of non-division
Longest part (18 to 24 hours)
The cell undergoes growth and growth and synthesis to get large enough to divide
77
What are the three phases of interphase?
G1 or gap 1 stage
S or synthesis stage
G2 or gap 2 stage
78
What is the G1 stage?
Immediately follows mitosis
The cell doubles in size
RNA, proteins, cell membranes, ribosomes, and other organelles in the cytoplasm are synthesized
Cell components lost in the previous cell division are replaced
Chromosomes are unduplicated (one molecule of DNA)
79
What is the synthesis stage?
Duplication (two identical daughter DNA molecules) of each chromosome occurs
The DNA is replicated and in fact doubles
Chromosomes are very long and diffusely spread throughout the nucleus
80
What is the G2 stage?
It is the interval following DNA replication and before mitosis
A second period of cellular growth occurs
The mitochondria divide
Precursors of spindle fibers are formed
81
Are there several checkpoints in the cell cycle to prevent a defective cell from going through mitosis?
Yes
At G1 stage to ensure readiness for DNA synthesis
At G2 stage to determine if cell is ready to enter mitosis and divide
If the damage to a cell is so severe that the cell cannot be repaired, the cell self-destructs by apoptosis (cell suicide) or necrosis
82
By the end of G2, what is the cell ready to do?
Divide
Mitosis
83
What is the second phase of the cell cycle?
Mitosis
84
What is mitosis?
The division phase
At the end of mitosis, each daughter cell receives one half, diploid number, of the doubled chromosome material that occurs prior to mitosis maintaining the same number of chromosomes as the mother cell
85
How many chromosomes are there before mitosis happens?
Double
92
86
Why do they need double the chromosomes before mitosis?
They need the correct number of cells when they divide
87
What will happen if one daughter cell has 3 chromosomes and the other one has one, and it continues to divide?
A chromosomal abnormality
88
What are the 4 phases of mitosis?
Prophase
Metaphase
Anaphase
Telophase
89
Is cytokinesis part of telophase?
Some people think it is
Some think its different
90
What is prophase?
At the beginning of prophase, chromosomes coil, thicken, and shorten and become recognizable as chromosomes
At the end of prophase, each replicated chromosome comprises two sister chromatids, both with the identical genetic information joined at the centromere
91
What are centrioles?
Located near the nucleus in non-dividing cells
Barrel-shaped structure made up of microtubules
Centrioles duplicate at the start of mitosis and each pair moves apart migrating to opposite poles of the dividing cell
Form poles of the mitotic spindle
92
What happens to the cells cytoskeleton during prophase?
It breaks down into subunits
Made up of the protein tubulin
From these subunits, a bridge of microtubules called the spindle apparatus forms between the two pairs of centrioles as they move apart
When the centrioles reach opposite ends of the cell, they extend microtubules in all directions
Anchors itself to the cell membrane
Called an aster
93
Is mitosis dependent upon the presence of centrioles?
No
94
How does metaphase begin?
With the complete disappearance of the nuclear membrane
95
What happens during metaphase?
Chromosomes are free in cytoplasm
Each chromosome consists of two parallel sub-units (sister chromatids) attached at the centromere, appearing X-shaped
Chromosomes move to the middle of the cell where the fully formed spindle fibers attach to the centromeres
Tension applied by spindle fibers aligns all chromosomes in one plane at the center of the cell
46 centromeres
Chromosomes in their most condensed form
96
Do you have double the amount of chromosomes you would normally have in metaphase?
Yes
97
What happens during anaphase?
At the beginning of anaphase attachments between the two sister chromatids break
Spindle fibers shorten, the homologous pairs of chromatids (daughter chromosomes) are pulled apart and begin moving to the opposite cell poles
At this point, each chromatid is considered a separate chromosome
At the end of anaphase a complete set of chromosomes is found at each end of the cell
98
Is anaphase the shortest phase of mitosis?
Yes
But it is one of the most critical because it ensures that each cell has the right number of chromosomes
99
Can genetic disorders occur during anaphase?
Yes
Due to abnormality of centromere function
100
What happens during telophase?
The daughter chromosomes arrive at the poles and the spindle fibers that have pulled them apart disappear
Membrane buds from the endoplasmic reticulum form a new nuclear membrane
Inside the new nucleus, the chromosomes uncoil, lengthen, and form threads and clumps of chromatin
101
What happens to spindle fibers when they are not needed?
They go away
102
Has the cell actually divided yet during telophase?
No
103
What is cytokinesis?
The last phase in the cell cycle
Division of the cytoplasm takes place
Cleavage forms and eventually divides the cell in two
Microtubules reorganizes into a new cytoskeleton
104
How many chromosomes does each daughter cell have?
46
They both receive one half of the doubled chromosome material
105
What does the cell do after cytokinesis?
Returns to interphase
Or goes into a rest phase
106
What is meiosis?
Division of germ cells
Chromosomes undergo one stage of replication and two stages of division
107
How many chromosomes does the cell start with in meiosis? (meiosis I)
46 chromosomes each with two chromatids
92 chromatids
108
What is meiosis I?
The reduction division
But the end of this there will be 23 chromosomes (46 chromatids) in each daughter cell
109
What happens during meiosis II?
The 23 chromosomes split at the centromere and the chromatids from each chromosome migrate to opposite poles
It is a reduction phase again
23 chromosomes (23 chromatids)
110
What is gametogenesis?
The generation of germ cells by meiosis
111
How many chromosomes does a daughter cell receive in mitosis?
A diploid set of 46 chromosomes
112
How many chromosomes does a daughter cell receive in miosis?
A haploid set of 23 chromosomes
113
How many daughter cells are produced at the end of meiosis?
4 not-identical daughter cells
114
How many daughter cells with a oocyte produce at the end of meiosis?
4
But only one will develop into a mature gamete
115
How many daughter cells with a spermatocyte produce at the end of meiosis?
4
All will become mature gametes
116
Do meiosis I and II consist of all of the phases of cell division?
Yes
116
Why are the meiosis daughter cells not identical?
Because we would all be clones of out parents if they weren't
We need variation, otherwise we'd have a weak gene pool
116
What is the first characteristic feature of meiosis I?
The pairing of homologous chromosomes (bivalents)
The pairing is exact except for the sex chromosomes
The homologous consists of 4 chromatids
116
What is the 2nd characteristic feature of meiosis I?
The cross over
Each chromosome will wrap around each other a swap genetic segments
117
When does the pairing and swapping occur in meiosis I?
During prophase I
118
What happens after they swap genetic information?
They separate and orient themselves to the spindle
In subsequent stages, the chromosomes migrate to the poles of the cell
119
At the end of meiosis I, how many chromosomes does each daughter cell contain?
It had one member of each chromosome pair
23 double structed chromosomes
The same number of a normal somatic cell
120
What happens during meiosis II?
The 23 double structured chromosomes divide at the centromere
Each newly formed daughter cell has 23 chromatids
Half the DNA of a somatic cell
121
When do the primordial germ cells appear in the wall of the yolk sac?
Embryonic stage
Week 3
122
When do the primordial germ cells migrate to the gonads of the embryo?
Week 4 or 5
123
What do the primordial germ cells differentiate into for a female embryo?
Oogonia
124
What happens to these primordial germ cells?
They continue to divide by mitosis
By the end of the third month, some of the oogonia differentiate into primary oocytes, while others continue to divide by mitosis
Immediately after their formation, the primary oocytes replicate their DNA and enter prophase 1
125
How many germ cells in the ovary are there by 5 months of development?
7,000,000
Degeneration begins and many oogonia and primary oocytes die
126
What phase do the cells enter at the time of birth?
All the surviving primary oocytes enter prophase of the first meiotic division at the time of birth
But instead of proceeding to metaphase, they enter the diplotene stage (resting)
127
Do primary oocytes remain in prophase?
Yes
They remain this way until puberty
128
What happens to the oocytes during puberty?
5 to 15 oocytes will mature with each ovarian cycle but only one typically will reach full maturity
The moment the oocyte enters metaphase II, ovulation occurs
129
Will the second maturation division happen if the oocyte is not fertilized?
No, the cell will degenerate and die
About 24 hours post ovulation
130
How many oocytes make it to puberty?
400,000 because many become atretic during childhood
Only 500 oocytes will be ovulated in the reproductive lifetime
131
Why do chromosomal abnormalities occur when you get pregnant later in life?
Theorized that the resting (dormant) stage of the oocyte is not the most protective against environmental influences
132
What is spermatogenesis?
All the events that transform the spermatogonia to spermatozoa
133
When does differentiation of germ cells begin for males?
Puberty
Females being in utero
134
What happens in spermatogenesis?
Primary spermatocytes enter a prolonged (22 days), prophase followed by completion of meiosis 1 and formation of secondary spermatozoa
Secondary spermatozoa immediately begin the second meiotic division and form spermatids containing haploid number of chromosomes
135
How long does it take a spermatogonium to form a spermatid?
64 days
136
What happens after the spermatid is formed?
Nucleus condenses and the cytoplasm is shed
Sperm cannot contribute mitochondria to the fertilized egg because of this
137
When do chromosomal abnormalities originate?
Meiotic division
138
What is an abnormal meiotic division?
When the two homologous pairs don't separate during the first meiotic division
Both pairs move into the daughter cell
Called nondisjunction
139
Can nondisjunction also happen in the second meiotic division?
Yes
One daughter cell receives 24 chromosomes and the other 22
140
What happens when an abnormal germ cell is fertilized?
The result is either 47 chromosomes (trisomy) or 45 (monosomy)
141
Can sex cells survive a monosomy?
Yes
But somatic cells cannot
