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MCAT > B 2 - Reproduction > Flashcards

B 2 - Reproduction Flashcards

1
Q

Define DIPLOID cells

A

Diploid (2n) cells have TWO copies of each chromosome

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2
Q

Define HAPLOID cells

A

Haploid (n) cells have ONE copy of each chromosome

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3
Q

What are the 5 stages of the CELL CYCLE

A 
G1 - presynthetic gap
S - synthesis
G2 - postsynthetic gap
M - mitosis
G0 - everyday function
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4
Q

Define CHROMATIN

A

DNA in an uncoiled form

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5
Q

What stages of the CELL CYCLE are termed INTERPHASE

A

G1, S & G2

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6
Q

Describe G1 stage

A

In G1 stage, cells create organelles for energy and protein production and increase their size

The RESTRICTION POINT, during which DNA is checked for quality, must be passed for the cell to move into the S stage

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7
Q

Describe S stage

A

In S stage, DNA is replicated. The strands of DNA, called CHROMATIDS, are held together at the centromere

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8
Q

Describe G2 stage

A

In G2 stage, there is further cell growth and replication of organelles in preparation for mitosis.

Another quality checkpoint must be passed for the cell to enter into mitosis

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9
Q

Describe M stage

A

Mitosis and cytokinesis occur

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10
Q

Describe G0 stage

A

In G0 stage, cell performs its functions without preparing for division

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11
Q

What is the role of the p53 protein in the CELL CYCLE

A

p53 plays a role in the two major checkpoints of the cell cycle (G1-to-S & G2-to-M)

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12
Q

Describe CYCLINS and CDKs

A

Cyclins and cyclin-dependent kinases (CDKs) rise and fall during the cell cycle.

Cyclins bind to CDKs, phosphorylating and activating TRANSCRIPTION FACTORS for next stage of the cell cycle

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13
Q

How does CANCER usually occur?

A

Cancer occurs when cell cycle control becomes deranged, allowing damaged cells ot undergo mitosis without regard to quality or quantity of hte new cells produced.

Cancerous cells may begin to produce factors that allow them to delocalize and invade adjacent tissues or metastasize elsewhere

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14
Q

What does mitosis produce?

A

Mitosis produces 2 genetically identical DIPLOID daughter cells from a single cell

occurs in SOMATIC CELLS

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15
Q

What are the 4 phases of MITOSIS?

A

Prophase
Metaphase
Anaphase
Telophase

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16
Q

Describe PROPHASE

A

In prophase, the chromosomes condense, the nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opposite sides of the cell, and the spindle apparatus begins to form

The kinetochore of each chromosome is contacted by a spindle fiber

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17
Q

Describe METAPHASE

A

Chromosomes line up along the metaphase plate (equatorial plate)

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18
Q

Describe ANAPHASE

A

Sister chromatids are separated and pulled to opposite poles

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19
Q

Describe TELOPHASE

A

Nuclear membrane reforms, spindle apparatus disappears, and cytosol and organelles are split between the two daughter cells thru cytokinesis

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20
Q

What type of cells can undergo MEIOSIS

A

Gametocytes (germ cells) only – reproductive cells

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21
Q

What does MEIOSIS produce?

A

meiosis produces UP TO four nonidentical haploid sex cells (gametes)

22
Q

How many rounds of replication and division does MEIOSIS have?

A

1 round of replication

2 rounds of division (reductional and equational)

23
Q

Describe what occurs in MEIOSIS 1?

A

In meiosis 1, homologous pairs of chromosomes (homologues) are separated from each other

24
Q

Define HOMOLOGUES

A

Homologues are chromosomes that are given the same number, but are of opposite parental origin

25
Describe PROPHASE 1
In prophase 1, the same events occur as in prophase of MITOSIS, except that homologues come together and intertwine in a process called SYNAPSIS The four chromatids are referred to as a TETRAD, and CROSSING OVER exchanges genetic material between one chromatid and material from a chromatid in the homologous chromosome. -- this accounts for MENDEL's SECOND LAW (OF INDEPENDENT ASSORTMENT)
26
Describe METAPHASE 1
Homologous chromosomes line up on opposite sides of the metaphase plate
27
Describe ANAPHASE 1
Homologous chromosomes are pulled to opposite poles of the cell. -- this accounts for MENDEL's FIRST LAW (OF SEGREGATION)
28
Describe TELOPHASE 1
The chromosomes may or may not fully decondense, and the cell may enter INTERKINESIS after CYTOKINESIS
29
Describe MEIOSIS 2
Sister chromatids are separated from each other in a process that is functionally identical to MITOSIS.
30
Define SISTER CHROMATIDS
Sister chromatids are copies of the same DNA held together at a centromere
31
Which chromosome is responsible for biological sex determination?
Biological sex is determined by the 23rd pair of chromosomes in humans, with XX being female and XY being male
32
Describe the X chromosome
X chromosome carries a sizeable amount of genetic information Mutations of X-linked genes can cause sex-linked disorders
33
Define HEMIZYGOUS
Males are defined as hemizygous with respect to unpaired genes on the X chromosome, so they will express sex-linked disorders, even if they only have one recessive disease-carrying allele
34
Define CARRIER
Women with one copy of a sex-linked recessive allele are called CARRIERS because they will not express the allele, but will carry it
35
Describe the Y chromosome
The Y chromosome carries little genetic information, but does contain the SRY (sex-determining region Y) gene, which causes the gonads to differentiate from the testes
36
How are male and female reproductive systems different?
Male contains both internal and external structures Female contains only internal structures
37
Describe the SCROTUM / TESTES
The testes are located in the scrotum, which hands outside of the abdominal cavity and has a temperature 2-4 degC lower than the rest of the body
38
Describe the EPIDIDYMIS
Once formed, sperm gain motility in the epididymis and are stored there until ejaculation
39
Describe EJACULATION
During ejaculation, sperm travel through the VAS DEFERENS to the ejaculatory duct, and then to the urethra and out through the penis
40
Describe SEMINAL VESICLES
The seminal vesicles contribute fructose to nourish sperm and produce alkaline fluid
41
Describe PROSTATE GLANDS
The prostate gland also produces alkaline fluid
42
Describe BULBOURETHRAL GLANDS
The bulbourethral glands produce a clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal
43
Describe SEMEN
Semen is composed of sperm and seminal fluid from the prostate/bulbourethral glands
44
Describe SPERMATOGENESIS
Four haploid sperm are produced from a SPERMATOGONIUM
45
Describe the different nomenclatures of germ cells in spermatogenesis
Primary spermatocyte - After S stage Secondary spermatocyte - After meiosis 1 Spermatids - after meiosis 2 Spermatozoa - after maturation
46
What 3 elements make up a sperm structure?
Head, midpiece and flagellum
47
Describe the HEAD of sperm
The head contains the genetic material and is covered with an acrosome -- a modified Golgi appartus that contains enzymes that help the sperm fuse iwth and penetrate the ovum
48
Describe the MIDPIECE of sperm
The midpiece generates ATP from fructose and contains many mitochondria
49
Describe the FLAGELLUM of sperm
The flagellum promotes motility
50
Describe the OVA
Ova are eggs that are produced in FOLLICLES in the OVARIES
51
What occurs each month to an OVA/egg?
Once each month, an egg is OVULATED into the PERITONEAL SAC and is drawn into the FALLOPIAN TUBE (OVIDUCT)

MCAT (8 decks)

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