Reproduction Flashcards
1
Q
What are diploids cells?
A
Autosomal cells that contains 2 copies of each chromosome
1
Q
What are haploids cells?
A
Contains 1 copy of each chromosome
2
Q
How many chromosomes a human has?
A
46, 23 from each parents
3
Q
What are the 4 stages of cell cycle?
A
G1, S, G2 and M. (G1, S and G2 are called the interphase)
4
Q
What is the interphase?
A
The phases of G1, S and G2 combined
5
Q
Where are cells who do not divide?
A
In an offshoot go G1, called G0
6
Q
What are cells doing in G0?
A
Carrying out their functions without any preparation for division
7
Q
During the interphase, how are DNA stored as?
A
Chromatin, a less condensed form of genetic material
8
Q
Why is the DNA stored as chromatin during interphase?
A
So the DNA is available for RNA polymerase to transcript genes
9
Q
During mitosis, how is DNA stored are? Why?
A
Tightly coiled chromosomes
So that no genetic material is lost during cell division
10
Q
What is happening in the first stage of interphase?
A
G1, cells create organelles for energy and protein production (mitochondria, ribosomes and endoplasmic retinaculum), while also increasing their size
11
Q
What is the other name for G1
A
Presynthetic gap
12
Q
What can one pass into the S (synthesis) phase?
A
By meeting certain criteria which is governed by the restriction point
13
Q
What is the restriction point?
A
The point where cells must meet criteria to pass from G1 to S
14
Q
What happens in the S phase?
A
Replication of genetic material, so the 2 daughter cells receive identical copies.
End result: each chromosome has 2 identical chromatids bound together by centromeres
15
Q
What is the ratio of DNA from cells in G1 to G2
A
G2 cells has twice DNA as G1 cells
16
Q
Does the ploidy of the cell changes after the replication of the genetic material?
A
No, even if a human would have 92 chromatids, there are still 46 chromosomes
17
Q
What is the other name for G2 stage?
A
Postsynthetic gap
18
Q
What happens in G2 stage?
A
The cell undergo another quality control checkpoint.
Make sure there is enough organelles and cytoplasm for 2 cells.
Also checks if the DNA has been replicated correctly
19
Q
What is the M phase?
A
Mitosis and cytokinesis
20
Q
What are the stages of mitosis?
A
Prophase, Metaphase, Anaphase and Telophase
21
Q
What is cytokinesis?
A
The splitting of the cytoplasm and the organelles between the 2 daughter cells
22
Q
What is the main protein in control of the control of the cell cycle specifically at both checkpoints?
A
p53
23
Q
What happens if the cells doesn’t undergo the criteria at the restriction point?
A
The cell cycle goes into arrest until the DNA has been prepared
24
What are the molecules responsible for the cell cycle?
Cyclins and cyclin-dependent kinases (CDK)
25
How can CDK be activated?
With the presence of the right cyclins
26
What happens to the concentration of cyclins during the cell cycle?
It increases and decreases during specific stages
27
What happens when the right cyclins bind to CDK?
It creates an activated CDK-cyclin complex, which then phosphorylate transcription factors
28
What transcription factors do once phosphorylate?
Promotes transcription of genes requires for the next stage of the cell cycle
29
What is the link between cell cycle control and cancer?
When cell cycle is deranged, damaged cell can undergo mitosis
30
What is the most common mutation found in cancer?
Mutation of the TP53, the gene that produce p53. The cell cycle is not stopped when the DNA is damages, so the mutations accumulate
31
What is the definition of the process of a tumor?
When a cell undergo rapid cell division
32
How can a tutor reach other tissue?
If the cell begins to produce the right factors (such as proteases that can digest basement membranes of factors that encourage blood vessel formation)
33
What is the definition of a metastasis?
When the cancerous cells can invade and spread through the bloodstream or the lymphatic system
34
In which type of cells do mitosis occurs?
Cells that are not involved in sexual reproduction
35
What are cells that are not involved in sexual reproduction called?
Somatic cells
36
What happens during the prophase?
The chromatin is condensed into chromosomes.
The centrioles separate and move towards opposites poles of the cell.
After migration, they will start to form spindle fibers (made of microtubule)
The nuclear membrane dissolves
37
What are spindle fibers made of?
Microtubules
38
What are asters?
A formation of microtubules that anchor the centriole to the cell membrane
39
Why does the nuclear membrane dissolves in the prophase?
In order for the spindle fibers to reach the chromosomes
40
What happens to the nucleoli in the prophase?
In becomes less distinct and sometimes may disappear completely
41
What are kinetochores?
Protein structures located on the centromere that serve as attachment point for specific fibers of the spindle apparatus (kinetochores fibers)
42
How many centrioles is there in a centrosome?
2
43
What is responsible for proper movement of the chromosomes during mitosis?
Centrioles
44
What happens in metaphase?
The kinetochores fibers interact with the fibers of the spindle apparatus to align the chromosomes at the metaphase plate (equatorial plate)
45
What is the metaphase plate? And what other name could it have?
The equatorial plate
Is the lign where it is equidistant from the 2 poles of the cell
46
What happens in anaphase?
Each centromere split allowing for 2 sister chromatids to separate from each chromosome.
They are then pulled towards opposite poles of the cells by the shortening of the kinetochores fibers
47
What makes the cells pulled towards opposite poles during mitosis?
The shortening of the kinetochores fibers
48
What happens in telophase?
It's like the reverse of prophase:
Spindle apparatus disappears
Nuclear membrane reformes around each of the chromosomes
Nucleoli reappear
49
What happens during cytokinesis?
Separation of cytoplasm and organelles in order for each daughter cell to have enough material to survive on its own
50
In which cells do meiosis occurs?
Gametocytes (germ cells)
51
What is the result of mitosis?
2 identical daughter cells
52
What is the result of meiosis?
4 non-identical sex cells
53
What is the main difference in the process of mitosis and meiosis?
Meiosis needs 2 rounds of divisions
54
What are the 2 rounds of divisions in meiosis?
The first one (Meiosis 1) creates 2 haploid cells by the separation of homologous chromosomes.
The second one (Meiosis 2) creates 2 cells out of each haploid cells without a change in ploidy
55
What type of division is Meiosis 1?
Reductional division, because there is a change in ploidy (from diploid to haploid cells)
56
What type of division is Meiosis 2?
Equational division, because there is no. change in ploidy
57
What happens in Prophase 1? (similarly and differently from prophase in mitosis)
Similarly: Chromatin condensed into chromosomes, the nuclear membrane disappears, the spindle apparatus forms
Differences: Synapsis and crossing over
58
What is the synapsis?
When 2 homologous chromosomes comes together and forms a tetrad in which homologous chromosomes are held together by a group of proteins (synaptonemal complex) and where it can form a chiasma and process in a crossing over
59
What is the name of the group of proteins that holds together the tetrad?
Synaptonemal complex
60
What is the chiasma?
The point of contact of 2 homologous chromosomes, where they can exchange equivalent pieces of DNA
61
What is the name of the process of exchange equivalent pieces of DNA at the chiasma?
Crossing over
62
How can crossing over be characterized?
By the number of events that occurs in one strand (by single or double-crossovers)
63
What is the definition of linkage?
The tendency for genes to be inherited together.
Genes that are located farther from each other are less likely to be inherited together
64
What is an advantage of crossing over in linkage?
Can unlink linked genes, thus increasing variety of genetic combinations
It is also believed to increase the ability of a specie to evolve and adapt to a changing environment
65
What law is explained by crossing over?
Mendel's second law (of independent assortment)
66
What happens in metaphase 1? (similarly and differently from mitosis)
Similar: Homologous pairs aligne at the metaphase plate and are each attached to a separate spindle fibre by its kinetochore
Different: Each chromosome is lined up by only one spindle fibre (not 2 from each poles like in mitosis)
67
What happens in anaphase 1?
Homologous pairs are separated and pulled to opposite poles of the cell (process called disjunction)
68
What is disjunction?
Where homologous pairs are separated and pulled to opposite poles of the cell in anaphase 1
69
What law accounts for the process of disjunction?
Mendel's first law (of segregation)
70
What is segregation?
The separation of 2 homologous chromosomes
71
What happens in telophase 1?
Nuclear membrane forms around each nucleus
72
What happens after telophase 1?
Cytokinesis (division in 2 daughter cells)
73
What in interkinesis?
A short rest period between cytokinesis and meiosis 2 in which the chromosomes partially uncoil
74
What is the difference between mitosis and meiosis 2?
Meiosis consist of sister chromatids to separate from each other (rather that homologues like in mitosis)
75
What is the end result of Meiosis 1?
2 haploids cells
76
How is the biological sex determined?
By the 23rd pair of chormosomes
77
How would you termed a male because it has only one copy of each gene in the X-chormosome
Hemizygous
78
What is the disadvantage for males to being hemizygous?
Since all the genes in the X-Chromosome have only one copy, if there was a disease-causing allele, it will necessarily express that allele
79
Do male or females express sex-linked diseases?
Male, because most of them diseases are recessively inherited
80
How do you call a female carrying a disease allele but not exhibiting the disease?
Carriers
81
What is the difference between the amount of genetic information between X and Y chromosomes?
X chromosomes carries a much bigger amount of genetic information
82
What is the role of the SRY gene and what it is?
Sex-determining region Y
This gene codes for a transcription factor that initiates testis differentiation and the formation of male gonads
83
What are the 2 functional components of the testes?
The seminiferous tubules and the interstitial cells of Leydig
84
What are the main functions of the 2 functional components of the testes?
Sperm are produced in the seminiferous tubules
Interstitial cells of Leydig secrete testosteron and other male sex hormones (androgens)
85
How are sperm nourished in the seminiferous tubules?
By the sertoli cells
86
Where are testes located?
In the scrotum, an external pouch below the penis
87
Why is the scrotum below the penis?
This position helps it maintain it's optimal temperature of 2 to 4 degrees lower than the body's temperature
88
What is the function of the layer of muscle around the vas deferens (ductus deferent)
Rise or lower the testes to maintain proper temperature for sperm development
89
What happens in the epididymis?
The sperm flagella's gain motility
90
What is the sperm route?
The are produced in the testes (seminiferous tubules) and are then passed to the epididymis to gain their flagella's motility and they are then stored until ejaculation.
During ejaculation, they passe through the vas deferent and enter the ejaculatory duct. The two ejaculatory ducts then fuse to form the urethra
91
What are sperm mixed with to pass through the reproductive tract?
Seminal fluis
92
By what is seminal fluid form?
Seminal vesicles, prostate gland and bulbourethral (Cowper's) gland
93
What is the contribution of each of the creators of the seminal fluid?
Seminal vesicles: fructose to nourish sperm
Seminal vesicles + prostate glands: gives the mildly alkaline properties of the fluid
Bulbourethral (Cowper's) glands: creates clear viscous fluid that cleans out any remnants of urine and lubricate the urethra during sexual arousal
94
What is the use of a mildly alkaline fluid for the seminal fluid?
So the sperm can survive in the relative acidity of the female reproductive tract
95
What is the mixture of sperm + seminal fluid called?
Semen
96
Where does spermatogenesis occurs?
In the seminiferous tubules
97
What are the names of each type of cells during spermatogenesis?
Diploid stem cells: spermatogonia
After S stage: Diploid primary spermatocytes
After Meiosis 1: haploid secondary spermatocytes
After Meiosis 2: haploid spermatids
Maturation: Spermatozoa
98
What are the components/parts of a spermatozoa?
A head, a midpiece and a flagellum
99
What are the functions of each part of the spermatozoa?
The head contains the genetic information
The midpiece is filled with mitochondria (generates ATP from fructose)
Flagellum: motility
Acrosome: Necessary to penetrate the ovum
100
What is an acrosome?
The cap covering the sperm head
101
What is the acrosome made from?
Derived from the Golgi apparatus
102
Can a male create more sperm after his puberty?
Yes, once a male reaches sexual maturity, it produce approx 3 million sperm per day for the rest of his life
103
What produces estrogen and progesterone?
Ovaries
104
What are the follicules?
Multilayered sacs that contains, nourish and protect immature ova
105
Where does an egg passes once it is ovulated?
First into the peritoneal sac.
Then drawn into the Fallopian tube (or oviduct)
Then the uterus
106
What propel the egg forward in the oviduct (Fallopian tube)?
Cilia
107
Where is the site of fetal development?
Uterus
108
What is called the external female anatomy?
Vulva
109
From interior to exterior, what are the female reproductive system anatomy?
Follicules, ovaries, peritoneal sac, fallopian tubes (oviduct), uterus, cervix, vaginal canal, vulva
110
What is the name of production of female gametes?
oogenenis
111
What is the difference between the supply in male and females?
Females have no unending supply of stem cells. All the oogonia a female will ever have are formed during fetal development
112
What is the process of oogenesis?
By birth, all the oogonia have already undergone replication, they are arrested in prophase 1 (primary oocytes)
Once a woman reaches menarches (first period), one oocyte per month will undergo meiosis 1 producing a secondary oocyte and a polar body
The secondary oocyte remains arrested in metaphase 2 until fertilization in which it can complete meiosis 2
113
What is the process called creating the polar body?
Unequal cytokinesis
114
What is unequal cytokinesis?
Process of giving all the cytoplasm needed for the daughter cell and nearly none to the other (which creates the polar body)
115
What happens generally to the polar body?
Usually will not divide any further and will never produce functional gametes
116
What are the 2 layers surrounding the oocytes?
Zona pellucida and Corona radiata
117
What are the roles of the 2 layers surrounding the oocytes?
Zona pellucida surrounds the oocytes itself and protects the oocytes while also containing compounds necessary for sperm binding
Corona radiate is outside of the zona pellucida and is a layer of cells that adheres to the oocyte during ovulation
118
What enzymes help the sperm cell to penetrate to oocyte?
Acrosomal enzymes
119
What does the ovum contributes to for the zygote?
Nearly everything: half DNA, all of the cytoplasm, organelles, RNA
120
What does the sperm contributes to for the zygote?
Half the DNA
121
What is the process of hormonal control over the ability to reproduce in general
Before puberty, the hypothalamus restrict production of GnRH (gonadotropin-releasing hormone)
At puberty, the restriction is lifter, the hypothalamus then release GnRH which then triggers the anterior pituitary gland to synthesize and release FSH (follicle-stimulating hormone) and LH (luteinizing hormone)
FSH and LH trigger the production of other hormones that develop and maintain the reproductive system
122
What is the process of hormonal control of sexual development in males?
During fetal period, the presence of Y-Chromosomes leads to production of androgens.
For infancy and childhood, androgen production is low.
During puberty, testosterone producing increase a lot and sperm production starts (with delicate interplay of FSH and LH on cells in the testes)
Testosterone production remains high during adulthood and decline as men age.
123
What are the effect of FSH and LH on testes?
FSH stimulates Sertoli cells: triggers sperm maturation
LH causes interstitial cells to produce testosterone
124
What are the effects of testosterone?
Develop and maintain male reproductive system + result in the development of the secondary sexual characteristics
125
What are the secondary sexual characteristics?
Facial and axillary hair, deepening of the voice, increase muscle and bone mall
126
What type of feedback exerts testosterone?
Negative feedback, it is kept in an appropriate range
127
What is the hormonal role of sexual development in females?
Ovaries are controlled by the FSH and LH produced by the anterior pituitary.
The ovaries produces estrogen and progresterone
128
What are the roles of estrogen?
Development and maintenance of the female reproductive system and females secondary sexual characteristics
In the embryo: development of the reproductive tract
In adults: thickening of the lining of the uterus (endometrium) each month
129
What are females secondary sexual characteristics?
Breast growth, widening of the hips, changes in fat distribution
130
What is the lining of the uterus?
Endometrium
131
What is the role of estrogen in regards to the endometrium?
Lead to its thickening every months in preparation for the implantation of a zygote
132
Which part secretes progesterone?
Corpus luteum
133
What is the corpus luteum?
The remains of the ovarian follicle following ovulation
134
What are the roles of progesterone?
Development and maintenance of the endometrium (but not its initial thickening)
135
Why does both estrogen and progesterone are needed to be able to support a zygote?
Between they both work on the endometrium
The estrogen does the thickening at each month
Progesterone develops and maintains the endometrium
136
What happens when the corpus luteum atrophies and ceases to function during pregnancy?
Progesterone is supplies by the placenta
137
When does the corpus luteum atrophies during pregnancy?
By the end of the first semester
138
What are the reproductive years of a female?
From menarche to menopause
139
What is the cycle name for the rise and fall of estrogen and progesterone levels in a cyclic pattern?
Menstrual cycle
140
What are the phases of menstrual cycle
Follicular phase
Ovulation
Luteal phase
Menstruation
141
What happens in the follicular phase?
GnRH from the hypothalamus increases (in response to lower estrogen and progesterone levels). Which leads to FSH and LH secretion.
They both work together to develop several ovarian follicles.
The follicles produces estrogen, which has a negative feedback on GnRh, FSH and LH
142
When does the follicular phase starts?
When the menstrual flow begins
143
What are the roles of estrogen during the follicular phase?
Stimulates regrowth of endometrial lining, stimulates vascularization and glandularization of the decidua
144
What happens during ovulation?
Estrogen reaches a threshold that results in a positive feedback (GnRH, FSH and LH levels spike
The surge in LH induces ovulation
145
What happens in the luteal phase?
LH causes the rupture follicle to form the corpus luteum which then secretes progesterone
Progesterone level rises, while estrogen level stays high
The high level of progesterone has a negative feedback on GnRh, FSH and LH, preventing the ovulation of multiple eggs
146
What happens during menstruation?
Corpus luteum loses its stimulation from LH, progesterone levels decline and the uterine lining is sloughed off.
The loss of high level estrogen and progesterone removes the block on GnRh, so the next cycle can begin
147
What happens if fertilization has occurred?
The zygote will develop into a blastocysts and will implant in the uterine lining and secrete human chorionic gonadotropin (hCG) which maintains the corpus luteum
By the second trimester, the hCG levels decline.
The high levels of estrogen and progesterone continues to serve as negative feedback on GnRH secretion
148
Why is the hCG (human chorionic gonadotropin) so important in the first trimester?
It maintains the corpus luteum, which secretes progesterone which keeps the uterine lining in place
149
Why does hCG (human chorionic gonadotropin) levels decline in the second trimester?
The placenta has grown to a sufficient size to secret enough progesterone and estrogen by itself
150
What happens during menopause?
As woman ages, her ovaries become less sensitive to FSH and LH, which leads to ovarian atrophy
As estrogen and progesterone levels also drops, the endometrium atrophies and menstruation stops
The blood level of FSH and LH rise (because of the negative feedback of estrogen and progesterone)
151
What physical and psychological changes usually accompany menopause?
Flushing, hot flashes, loading, headaches and irritability
152
At what age menopause usually occurs?
Between 45 and 55
