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Biology > Chapter 2: Reproduction > Flashcards

Chapter 2: Reproduction Flashcards

1
Q

The Cell Cycle: G1 Stage

A

“Presynthetic Gap” Phase

the cell grows and performs its normal functions

DNA is examined and repaired

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2
Q

The Cell Cycle: S Stage

A

“Synthesis of DNA” stage

DNA is replicated

each chromosome will consist of 2 identical chromatids attached at the centromere

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3
Q

The Cell Cycle: G2 Stage

A

“Postsynthetic Gap” Stage

the cell continues to grow and replicates organelles in preparation for mitosis

the cell continues to perform its normal functions

cells entering G2 have twice as much DNA as they did in G1 (chromosomes number is the same, however they are each duplicated)

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4
Q

The Cell Cycle: M Stage

A

“Mitosis” phase
- consists of mitosis and cytokinesis

Mitosis: includes prophase, metaphase, anaphase and telophase

Cytokinesis: the splitting of the cytoplasm and organelles into 2 daughter cells

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5
Q

The Cell Cycle: G1/S checkpoint

A

“The restriction point”

  • the cell determines if the DNA is in good condition for synthesis
  • the cell will not continue into the S phase if the DNA is damaged
  • p53 is the main protein involved in this checkpoint
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6
Q

The Cell Cycle: G2/M Checkpoint

A
  • the cell ensures it has achieved adequate size and organelles have been properly replicated to support 2 daughter cells and that DNA has been correctly replicated
  • p53 protein plays a role in this checkpoint
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7
Q

Cyclins and Cyclin-dependent Kinases (CDK)

A
  • concentrations of various cyclins increase/decrease during specific stages of the cell cycle
  • cyclins bind to CDKs to create an activated CDK-cyclin complex
  • this complex can then phosphorylate and activate transcription factors for the next stage of the cell cycle
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8
Q

Transcription Factors

A

promote transcription of genes required for the next stage of the cell cycle

phosphorylated by CDK-cyclin complexes

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9
Q

Explain how a TP53 mutation causes cancer.

A

TP53 is a mutation of the gene which produced p53

  • recall: p53 is involved in the G1/S checkpoint which checks for DNA damage prior to replication

when this gene is mutated, the cell cycle is not stopped to repair damaged DNA. a cell continuously divides despite existing mutations.

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10
Q

Tumors

A

created when cancer cells rapidly undergo cell division

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11
Q

Metastasis

A

the spread of cancerous cells spread to distant areas of the initial cancer site through the bloodstream or lymphatic systems

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12
Q

Mitosis definition and phases

A

Mitosis: the process by which 2 identical daughter cells are created from a single cell; occurs in somatic cells

Phases: prophase, metaphase, anaphase, telophase

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13
Q

List 5 things that occur during prophase of mitosis

A

chromatin condenses into chromosomes

the centriole pairs separate and move towards opposite poles of the cell

the spindle fibres and astral rays form

the nuclear membrane dissolves and nucleoli disappears

kinetochores appear at the centromere

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14
Q

List 2 things that occur during metaphase of mitosis

A
  • the centrioles are now at opposite ends of the cell
  • the kinetochore fibres interact with the fibres of the spindle apparatus to align the chromosomes at the metaphase plate (equatorial plate)
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15
Q

What occurs during anaphase of mitosis

A
  • the sister chromatids separate and are pulled towards the opposite poles of the cell by the shortening of the kinetochore fibers
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16
Q

List 5 things that occurs during telophase of mitosis

A

the spindle apparatus disappears

the nuclear membrane reforms around each set of chromosomes

the nucleoli reappear

chromosomes uncoil

cytokinesis occurs at the end of telophase

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17
Q

Define Cytokinesis

A

the separation of the cytoplasm and organelles so that each daughter cell has sufficient supplies to survive on its own

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18
Q

The Cell Cycle: G0 Stage

A

the cell preforms its normal functions and is not preparing for division

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19
Q

What is the chromosome complement of animal autosomal cells

A

diploid (2n); they contain 2 copies of each chromosome

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20
Q

What is the chromosome complement of animal germ cells (reproductive cells)

A

haploid (n); they contain only 1 copy of each chromosome

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21
Q

What is the diploid and haploid number in humans?

A

diploid: 46
haploid: 23

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22
Q

The Cell Cycle: Interphase

A

consists of G1, S, and G2 stages

the longest part of the cell cycle
- even actively dividing cells spend 90% of their time in this stage

DNA is in its less condensed chromatin state and are not visible with light microscopy
- purpose: so that the DNA can be transcribed

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23
Q

Define meiosis

A

meiosis occurs in gametocytes (germ cells) and results in up to 4 non-identical (unique) gametes (sex cells)

consists of 1 round of replication and 2 rounds of division

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24
Q

Meiosis I

A

homologous chromosomes are separated, generating haploid daughter cells

“reductional division”

25
Q

Meiosis II

A

sister chromatids are separated

“equational division”

26
Q

Homologous chromosomes vs sister chromatids

A

homologous chromosomes: a pair of chromosomes with the same genes but varying alleles; one is of paternal origin while the other is of maternal origin

sister chromatids: duplicated chromosomes which contain identical DNA and are held together at the centromere

27
Q

How many chromatids, chromosomes, and homologous paris does a human cell contain after the S phase?

A

46 chromosomes (duplicated)

92 chromatids

23 homologous pairs

28
Q

Hemizygous

A

males are hemizygous for many genes on the x chromosome, meaning they only carry one copy of those genes

29
Q

Define X-linked (sex-linked) disorders and the differences in expression between males and females

A

mutations to genes carried on the X chromosome

males

  • are hemizygous for many of these genes
  • the allele they possess will determine their phenotype (one copy of a recessive disorder will result in the disorder)

females:

  • may be homozygous or heterozygous for genes on the x chromosomes
  • express recessive x-linked disorders less frequently than males

carriers: females carrying a diseased allele on an x-chromosome but not exhibiting the disease

30
Q

SRY (sex-determining region Y) gene

A

a gene located on the Y-chromosome which codes for a transcription factor that initiates testis differentiation and the formation of male gonads (testes)

in the absence of the y-chromosome, zygotes become female
in the presence of the y-chromosome, zygotes become male

31
Q

Name the 2 functional components of the testes and their function?

A

seminiferous tubules
- location where Sertoli cells nourish sperm during their development

interstitial cells of Leydig
- secrete testosterone and other male sex hormones (androgens)

32
Q

Where is sperm produced within the testes?

A

within the highly coiled seminiferous tubules

nourished by Sertoli cells

33
Q

Where are the testes located?

A

in the scrotum, an external pouch which hangs below the penis

34
Q

What is the temperature of the testes maintained at and how?

A

the testes maintain a temperature 2-4 C lower than the body

a layer of muscle surrounding the vas deferent can raise and lower the testis to maintain the proper temperature for sperm development

35
Q

Where are sperm stored following formation?

A

as sperm are formed, they pass to the epididymis where their flagella gain motility

they are stored here until ejaculation

36
Q

Describe the pathway of sperm prior to and during ejaculation.

A

prior to ejacualtion
- as sperm are formed, they are passed to the epididymis where their flagella gain motility; they are stored here until ejaculation

during ejaculation

  • sperm travel through the vas deferent to the ejaculatory duct
  • the two ejaculatory ducts fuse to form the urethra, which carries the sperm through the penis as they exit the body
37
Q

Where is the ejaculatory duct located?

A

at the posterior edge of the prostate gland

38
Q

Seminal fluid is produced through a combined effort of the __________.

A

seminal vesicles

  • contribute fructose to nourish the sperm
  • provide the fluid with mildly alkaline properties so the sperm can survive the relative acidity of the female reproductive tract

prostate gland
- provide the fluid with mildly alkaline properties so the sperm can survive the relative acidity of the female reproductive tract

bulbourethral (Cowper’s) glands
- produce a clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal

39
Q

The combination of sperm and seminal fluid is known as ______.

A

semen

40
Q

Define spermatogenesis and where it occurs.

A

the formation of haploid sperm through meiosis

results in 4 functional sperm for each spermatogonium

occurs in the seminiferous tubules

41
Q

Spermatogonia

A

the diploid stem cells in males

42
Q

Primary spermatocytes are ______ (diploid or haploid).

A

diploid

43
Q

Secondary spermatocytes are ______ (diploid or haploid).

A

haploid

44
Q

Spermatids

A

haploid

resulting following meiosis II of secondary spermatocytes

45
Q

Spermatids undergo maturation to become _____________.

A

mature spermatozoa

46
Q

What are the 3 structural components of a mature sperm cell and their functions?

A

head: contains the genetic material; covered by an acrosome cap
midpiece: generates ATP from fructose; filled with mitochondria
flagellum: motility

47
Q

What is an acrosome, where is it derived from, and what is its purpose?

A

the cap which covers each sperm head

derived from the Golgi apparatus (it is a modified Golgi apparatus)

contains enzymes capable of penetrating the cotton radiate and zone pellucid of the ovum, permitting fertilization to occur

48
Q

How many sperm are produced per day in a sexually mature male?

A

approximately 3 million

49
Q

What are the female gonads?

A

ovaries

50
Q

What are the 2 major hormones produced by the ovaries?

A

estrogen and progesterone

51
Q

Describe the female reproductive anatomy.

A

the ovaries

  • located in the pelvic cavity
  • consist of follicles which contain, nourishments and protect the immature eggs

one egg per month is ovulated into the peritoneal sac

the egg is then drawn into the fallopian tube (oviduct)
- lined with cilia to propel the egg forward

the fallopian tubes are connected toe the uterus, the site of fetal development

the cervix is the lower end the uterus which connects to the vaginal canal

the vulva is the external female anatomy

52
Q

What is oogenesis and when does it occur?

A

oogenesis is the production of the female gametes

all of the oogenia a woman will ever have are formed during fetal development; by birth, all of the oogonia have undergone DNA replication and are considered primary oocytes arrested in prophase I

53
Q

What is menarche?

A

a women’s first menstrual cycle

54
Q

One _______ per month will complete _____ to produce a ___________.

A

primary oocyte

meiosis I

secondary oocyte and a polar body

55
Q

During which phase of meiosis is a primary oocyte arrested?

A

prophase I

56
Q

During which phase of meiosis is a secondary oocyte arrested?

A

metaphase II (until fertilization)

57
Q

What is a polar body?

A

the division of a primary oocyte is characterized by unequal cytokinesis, giving plenty cytoplasm to one daughter cell (the secondary oocyte) and nearly no cytoplasm to the other (the polar body)

the polar body will not divide further and never produces functional gametes

58
Q

What are the 2 layers surrounding oocytes?

A

the zone pellucid

the corona radiata

59
Q

Describe the zona pellucida.

A

surrounds the oocyte itself

an acellular mixture of glycoprotein that protect the oocyte and contains compounds necessary

Biology (11 decks)

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