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MCAT Biology > Chapter 2 > Flashcards

Chapter 2 Flashcards

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1
Q

Cell Cycle

A

Actively dividing cells: Interphase
1. G1
* G0: Cell is living and serving its function, not preparing to divide
2. S
3. G2
4. M

Chromatin: less condensed chromosomes during Interphase

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2
Q

G1 Stage (Presynthetic Gap)

A

Cell grows and performs its normal functions and DNA is examined/repaired
* Create organelles for energy and protein production
* Increasing size
* Have to pass restriction point (specific criteria, ex: proper DNA complement)

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3
Q

S Stage (DNA Synthesis)

A
  • Replicates DNA so daughter cells have identical copies
  • Chromosome made of two chromatids bound together at centromere
  • Still have 46 chromosomes (don’t double bc/ two chromatids)
  • Last point at which something can be added to DNA and replicated
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4
Q

G2 Stage (Photosynthetic Gap)

A

Cell continues to grow and replicates organelles to prepare for mitosis while performing normal functions
* Cell pases through quality checkpoint
* Makes sure correct organelles and cytoplasm and enough to divide
* Makes sure DNA replicated correctly

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5
Q

M Stage (Mitosis)

A

Mitosis & Cytokinesis
* Occurs in somatic cells (cells not involved in sexual reproduction)
Mitosis Phases:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Any change to any of the mitosis stages would lead to a fail in the cycle preventing cell division

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6
Q

Cyclin & Cyclindependent kinases (CDK)

A

Molecules responsible for cell cycle
* Phosporylates transcription factors

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7
Q

Transcription factors

A

Promote transcription of genes require for the next stages of cell cycle

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8
Q

Cancer

A

Result of faulty cells being allowed to undergo mitosis

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9
Q

Prophase

A
  • First phase in Mitosis
  • Condensation of chromatin in to chromosomes
  • Centrioles (located in centrosome) seperate and move to opposite poles
  • Centrioles: Responsible for correct division of DNA
  • Spindle fibers form and interact with kinetochore
  • Nucleoli disappear
  • Nuclear membrane dissolves
  • Kinetochores appear
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10
Q

Metaphase

A
  • Centriole pairs move to opposite ends of cell
  • Spindle fibers and kinetochore fibers move chromsomes to metaphase plate (middle)
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11
Q

Anaphase

A
  • Centromeres split so each chromatid has own centromere
  • Sister chromatids seperate
  • Sister chromatids pulled to opposite ends of cell
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12
Q

Telophase

A
  • Reverse of prophase
  • Cell divides into identical daughter cells
  • Spindles disappear
  • Nuclear membrane reforms around chromosomes
  • Nucleoli reappear
  • Chromosomes uncoil
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13
Q

Cytokinesis

A
  • Seperation of cytoplasm and organelles so daughter cells have enough to survive on their own
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14
Q

Meiosis

A
  • Occurs in gametocytes (germ cells) and results in up to four identical sex cells (gametes)
  • One round of replication
  • Two rounds of division
    Meiosis I: Reductional division homologous chromsomes being seperated generating haploid daughter cells
    Meiosis II: equational division seperation of sister chromatids
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15
Q

Meiosis I

A

Two halpoid daughter cells

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16
Q

Meiosis II

A

Four haploid daughter cells

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17
Q

Homologous chromosomes

A

Related chromosomes of opposite parental origin (one mom chromosome one dad chromsome)

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18
Q

Sister chromatids

A

Identical copies of the same DNA held together at centromere

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19
Q

Mitosis vs Meiosis

A
20
Q

X Chromsome

A
  • Females only have X
  • Males have X and Y
  • Mutations can lead to sex-linked (X-linked) disorders
21
Q

Hemizygous

A

Only having one copy of a gene
* Males with genes on X chromsome

22
Q

Carriers

A

Females carrying a diseased allele on an X chromsome but not exhibiting the disease

23
Q

Y Chromosome

A

Contains very little genetic information
* Notable gene is SRY (sex-determing region Y) which initiates the formation of male gonads

24
Q

Interstitial cells of Leydig

A

Secrete testosterone and other male sex hormones (androgens)

25
Q

Sertoli Cells

A

Nourish Sperm during development

26
Q

Prophase I

A

Primary oocyte arrested

27
Q

Metaphase II

A

Secondary oocyte arrested

28
Q

Acromosome

A

Contains enzyme that can penetrate corona radiata and zona pellucida of ovum, allowing fertilization
* Modified golgi apparatus

29
Q

Phases of Menstrual Cycle

A
  1. Follicular
  2. Ovulation
  3. Luteal
  4. Menses
30
Q

Follicular Phase

A
  • Egg develops
  • Endometrial lining becomes vascularized and glandularized
  • FSH goes up
  • LH stays the same
  • Estrogen drops then goes up
  • Progesterone goes down
31
Q

Ovulation Phase

A
  • Egg is released from follicle into peritoneal cavity
  • FSH goes up
  • LH goes up a lot
  • Estrogen goes up
  • Progesterone goes down
32
Q

Luteal Phase

A
  • Corpus lumen produces progesterone to maintain endometrium
  • FSH goes down
  • LH stays the same
  • Estrogen goes up
  • Progesterone goes up
33
Q

Menses Phase

A
  • Shedding of endometrial lining
  • FSH goes down
  • LH goes down
  • Estrogen goes down
  • Progesterone goes down
34
Q

Sperm Cell Development

A

spermatogonium > 1˚ spermatocyte > 2˚ spermatocyte > spermatid > spermatozoan

35
Q

Egg Cell Development

A

Ovulation (egg cell completed meiosis I) > Metaphase II (stopped as haploid cell/secondary oocute)
* Will complete Meiosis II when penetrated by sperm

36
Q

Estrogen

A
  • Causes growth of endometrial lining
  • High level during luteal phase to promote vascularization/glandularization of tissue
  • Excessive levels could lead to tumor formation
37
Q

Ovulation

A

Ovulates > abdominal cavity/peritoneal sac > fallopian tube/oviduct > uterus (site of fetal development) > cervix > vaginal canal

38
Q

Seminal vesicles

A

Produce alkaline fructose-containing secretions

39
Q

Epididymis

A
  • Site of sperm maturation at posterior side of testis
  • Sperm gain mobility and are stored until ejaculation
40
Q

Vas deferens

A
  • Surrounded by muscle that raises and lowers the testis to maintain constant temperature suitable for sperm production
  • Tube connecting epididymis to lower testes
41
Q

Cowper’s glands

A

Produce a fluid to clear traces of urine in uretha

42
Q

Telophase I

A

Last point in meiotic cycle that a cell has a diploid number of chromosomes
* Cytokinesis occurs
* End of telophase I results in two haploid daughter cells

43
Q

Genetic variability

A
  • Random fertilization of an egg by sperm
  • Random segregation of homologous chromsomes during Anaphase I
  • Cross over between homologous chromosomes during Prophase I
44
Q

Anaphase I

A

First meiotic division that seperates homologous chromosomes to opposite poles of cell

45
Q

Nondisjunction

A

Incorrect segregation of homologous chromsomes during Anaphase I or of sister chromatids during Anaphase II
* One daughter cell has two copie sof related genetic material and the other recieves 0
* Abnormal complement of chromosomes (not 46)

46
Q

hCG (human chorionic gonadotropin)

A
  • Preserves corpus lutuem
  • Maintained during first trimester

MCAT Biology (8 decks)

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