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yr.11 Human Biology > Reproduction > Flashcards

Reproduction Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Haploid number

A 
23 chromosomes (in humans)
Half amount of chromosomes as original cell
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2
Q

diploid

A

has same amount of chromosomes as parent cell

46 (in humans)

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3
Q

Homologous chromosomes

A

chromosomes in diploid cells exist in pairs that are identical in shape and carry genetic information that influences the same characteristics

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4
Q

Meiosis

A

2 nuclear divisions

Creates 4 unique daughter cells

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5
Q

meiosis stages

A

Interphase
first division
Second division

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6
Q

First division

A

Homologous pairs off during prophase
during prophase 1, chromosome visible as long threads, already done DNA replication, therefore pair of chromatid
Chromosomes gradually move so pair of homologous chromosomes come to lie alongside each other through out entire length.
chromosomes then shrink and thicken as DNA becomes more tightly coiled.

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7
Q

Crossing over

A

when homologous chromosomes paired, chromatids may cross, break and exchange segments
occurs in meiosis
Creates new combination of genes so chromosomes passed on to offspring aren’t exactly same as one inherited from parents

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8
Q

Chiasma

A

point where two chromatids cross over

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9
Q

recombination

A

New combination of alleles along the chromosome due to crossing over

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10
Q

non-disjunction

A

One or more chromosomes may fail to seperate when cell divides
in second meiotic division one or more chromosomes may fail to seperate, results in daughter cell having extra chromosome and other lacking one.

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11
Q

Trisomy

A 
inherits extra copy of a chromosome 
Down syndrome (trisomy 21), extra chromosome in chromosome 21
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12
Q

Monosomy

A

individual missing one chromosome

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13
Q

Partial monosomy

A

part of chromosome is missing

Therefore 1 copy

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14
Q

partial trisomy

A

Part of extra chromosome is attached to one other chromosome

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15
Q

random (independent) assortment

A

When chromosomes are separating to each pole during first meiotic division
Happens independently, copy of chromosome 1 cell receives in no way influences which copy of chromosome 5 cell receives.

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16
Q

testes

A

Where spermatozoa are produced
Lay outside of body cavity as optimum temp for sperm production is 2C less then body temp.
oval shaped, 4.5cm long, 2.5cm wide, 3cm thick.
Divided into 200-300 lobules, lobules filled with seminiferous tubules.

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17
Q

scrotum

A

Skin covered pouch holding and supporting the tests

two pouch surrounding each test

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18
Q

epididymus

A

Seminiferous tubules join and eventually form duct.
highly folded structure at rear of each teste
5-6m long

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19
Q

Seminiferous

A

cells in seminiferous create spermatogenesis

Between seminiferous and epididymus are cells making testosterone called interstitial cells.

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20
Q

vas deferens (sperm duct)

A

Tubule after epididymus
carries sperm away from testes
Both vas deferens join at urethra

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21
Q

urethra

A

Duct for transporting urine and sperm

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22
Q

semen

A

Liquid nourishes and aids transport of sperm

secretion of three glands: seminal vesicle, prostate gland, bulbo-urethral gland

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23
Q

Seminal vesicle

A

secrete thick fluid rich in sugars making 60% of sperm volume

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24
Q

Prostate gland

A

secretes thin, milky, alkaline fluid

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25
Q

Bulbo-urethral gland

A

secrete clear mucous

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26
Q

Erectile tissue

A

sponge like spaces in the tissue

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27
Q

Ovaries

A

produce female gametes

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28
Q

Ova

A

female egg

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29
Q

Stroma

A

connective tissue making up ovary

Surrounded by egg cells, each cell inclosed in follicle.

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30
Q

uterine tubes (Fallopian tubes/oviducts)

A

Where egg is expelled from ovaries to uterus

one extends from each ovary

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31
Q

Fimbrea

A

tiny finger-like projections
Push egg into Fallopian tubes
funnel-like opening next to ovaries

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32
Q

Cilia

A

move egg along Fallopian tubes

Contractions along tube walls also aid in movement

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33
Q

uterus

A

Single, hollow, pear-shaped organ
behind urinary bladder
Held in pelvic cavity by ligaments allowing some movement
smooth muscle walls

34
Q

Endometrium

A

soft mucous membrane lining in uterus

35
Q

Cervix

A

neck of the uterus

Protrudes into vagina

36
Q

vagina

A

Canal leading to outside of the body
capable of stretching
10cm long
Lined with mucous membranes

37
Q

hymen

A

Opening of vagina (found at)

fold of tissue

38
Q

Vulva

A

vagina’s opening to exterior

Made of: labia majora, labia minora and clitoris

39
Q

labia majora

A

Two fleshy folds of skin
made of fat and fibrous tissue
Contains large number of mucous membranes producing oily secretions

40
Q

labia minora

A 
Two smaller folds of skin, beneath and under majora
pinkish in colour
Without fat 
lacking pubic hair
Suround where urethra and vagina open
41
Q

clitoris

A

Contains erectile tissue, blood vessels and nerves

very sensitive to touch, engorged with blood when stimulated

42
Q

Gametogenesis

A

gamete development, from meiosis to mature gametes
2 types:
Spermatogenesis, formation of spermatozoa in testis
Oogenesis, formation of Ova in ovary

43
Q

spermatogenesis

A

Occurs in seminiferous tubules of each teste
Seminiferous tubules lined with spermatogonia, containing diploid number
process takes 72 days

44
Q

spermatogenesis at puberty

A

Spermatogonia begin dividing by mitosis
provides continuous production of spermatozoa
Some daughter cells pushed to tubules, undergo growth

45
Q

Process of spermatogenesis

A

spermatocytes are enlarged spermatogonia cells.
primary spermatocyte, have diploid number.
Primary undergoes meiotic devision and become secondary spermatocyte, haploid
second meiosis division occurs of secondary forming spermatids.
4 haploid spermatids made from 1 diploid spermatogonia

46
Q

Last stage of spermatogenesis

A

spermatids mature into spermatozoa
Cytoplasm mostly lost
tail containing contractile material forms
Maturing spermatozoa nourished by special cells extending from outer portion of seminiferous tubule into the centre.

47
Q

spermatogonia

A

Immature cells lining seminiferous tubules

48
Q

sperm

A

0.06mm long
Head consists of nuclear material, fluid vesicle at its tip called acrosome, in fluid are enzymes important if sperm reaches egg.
enzymes break down layer of cells surrounding the egg so fertilisation can occur.
Neck lies in-between head and middle-piece
middle-piece contains mitochondria, thin layer of cytoplasm around mitochondria, short life span due to little cytoplasm, receives nourishment from semen.
Tail is capable of contractile motion to propel cell forward.

49
Q

oogenesis

A

Involves maturation and meiosis
when body born, million of egg mother cells, call oogonia.
Oogonia develop in uterus

50
Q

oogonia

A

Diploid

under mitosis and develop into ova

51
Q

Oogenesis at birth

A

each ovary contains several thousand oogonia, have gone through growth phase to become primary oocytes.
Primary oocytes begin prophase of first meiotic division and stop there, at birth they are still in prophase.
primary follicle is what surrounds primary oocytes, it is a single layer of cells.

52
Q

Oogenesis at puberty

A

process of follicle growth and maturation begins.
As follicles mature, oocytes contained undergo first meiotic division, producing two haploid cell, cells are unequal size.
larger cell receives half chromosomes and most of cytoplasm, is called secondary oocyte
Smaller cell receives half chromosome but little cytoplasm, is called primary oocyte
secondary oocyte begins second meiotic division but stops at metaphase

53
Q

Ovulation

A

follicle ruptures, expelling secondary oocyte along with polar body (primary oocyte)
Secondary enters uterine tube, if penetrated by spermatozoa, meiosis is completed.
secondary meiotic division cells also produce 2 haploid cells, equal size.
Larger becomes ovum, mature cell
smaller becomes secondary polar body.
Primary polar body may also undergo second meiotic division, all polar bodies disintegrate.

54
Q

oogenesis summary

A

Produces a single ovum from each oocyte, but three polar bodies which disintegrate.

55
Q

endocrine gland

A

Menstrual and ovarian cycle depends on it, for regulation and control
glands release hormones into extracellular fluid that surrounds cells making up the gland
Secretions usually pass into capillaries, to be transported by blood where circulation reaches target organ.
main targets are testis and ovaries.

56
Q

Reproductive hormones

A

gonadotrophic hormones
Prolactin
oxytocin
Testosterone

57
Q

pituitary gland

A

Small organ lying in a pit in bone marrow below brain and above roof of mouth.

58
Q

gonadotrophic hormones (gonadotropins)

A

Targets the gonads

2 types: Follicle stimulating hormone, luteinising hormone

59
Q

Follicle stimulating hormone (FSH) females

A

stimulates development and maturation of ovarian follicle in females
During development, ovarian follicle secretes oestregen, FSH decreases as oestrogen increases in blood.

60
Q

luteinising hormone (LH) females

A

Promotes final maturation of the ovarian follicle, ovulation, and formation of corpus luteum.
corpus luteum secretes progesterone, as well as oestrogen, gradual decrease of LH secretion as progesterone in blood increases

61
Q

Prolactin

A

Secreted by pituitary gland
affects breasts
Important in preparation and maintenance of milk production

62
Q

oxytocin

A

Secreted by pituitary gland
causes uterine contractions
Promotes movement of milk in breast
role in movement of sperm and production of testosterone in testes

63
Q

FSH in males

A

Stimulates epithelial tissue of seminiferous tubule in testes to produce sperm

64
Q

LH in males

A

Stimulates cells in test to secrete testosterone

65
Q

testosterone

A

Development of immature sperm cells to spermatozoa

Major role in maintenance of male reproductive organs and sex drive

66
Q

at puberty

A

Gonadotrophic hormones stimulate changes physical and psychological
in females, sexual maturation brought by oestrogen
In males, sexual maturation Brough by testosterone

67
Q

ovarian cycle

A

Series of events taking place in ovaries
includes maturation of eggs and its release into uterine tube.
Development of follicles in ovary and formation of corpus luteum.
20-40 days
When sexual maturity at puberty reached, some primary follicles undergo further development

68
Q

First half of ovarian cycle

A

levels of FSH and LH slowly increase, prompting growth and maturation on follicles over 10-14 days

69
Q

4 steps of follicle development

A
  1. Cells forming wall of primary follicle begin to enlarge and divide, creating layer of cells around developing oocyte
  2. Secretions from these cells create fluid-filled space that gradually forces the oocyte to edge of the follicle (secondary follicle)
  3. As more fluid accumulates within follicle, it continues to enlarge and gradually moves towards the surface of the ovary
  4. On reaching surface, it provides a bulge that looks like a swollen blister on the surface of the ovary (mature follicle)
70
Q

Follicle development

A

several secondary follicles may commence development, but usually only one completes development
As follicles grow, high release of oestrogen and low progesterone

71
Q

Day 14 of ovarian cycle

A

Level of oestrogen high enough to spike LH and FSH
surge in LH causes ovulation of the most mature follicle.
Other follicles degenerate

72
Q

At ovulation

A

Mature follicle burst and expels oocyte
open end of uterine tube funnels over ovary, cilia in funnel create current so egg enters tube.
Only one follicle matures at a time therefore one oocyte is released
egg gradually pushed down uterine tube towards uterus by cilia

73
Q

Following ovulation

A

ruptured follicle collapses and blood within clots, clot gradually absorbed by remaining follicle cells forming corpus luteum.
Corpus luteum is cream-coloured body
corpus luteum secretes oestrogen and progesterone
Progesterone influences development of the lining of the uterus, preparing it for implantation if fertilisation occurs.
also inhibits secretion of LH and FSH, preventing follicle development.

74
Q

If not fertilised (ovarian cycle)

A

corpus luteum reaches max development at 8-10 days after ovulation.
Then degenerates into fibrous mass of scar tissue, corpus albicans, which eventually disappears.
New ovarian cycle commences due to reduction in oestrogen and progesterone

75
Q

if fertilised (ovarian cycle)

A

Ovarian cycle ceases
corpus luteum continues to develop
Human chorionic gonadotropin (HCG) maintains corpus luteum, is a hormone produced in placenta.
once placenta is able to secret oestrogen and progesterone, corpus luteum begins disintegration.
Degeneration is slow, still present in ovary after child birth.
ovarian cycle recommences once breastfeeding is complete

76
Q

Menstruel cycle

A

occurs during ovarian cycle
Changes in uterine lining (endometrium), preparation for developing embryo in case of fertile egg is released from ovulation
takes place over several days
Day 1 of the cycle

77
Q

first stage of menstrual cycle

A

While follicle maturing in ovarian cycle, progesterone causes endometrium of uterus to become thicker and softer.
also an increase in number of blood vessels and mucous secreting glands

78
Q

After ovulation (menstrual cycle)

A

endometrium continues to thicken

Glands within secrete water mucous rich in glycogen

79
Q

if not fertilised (menstrual cycle)

A

Corpus luteum degenerates, reduces progesterone resulting in its break down.
14 days after ovulation, blood from broken down capillaries, mucous secretions and cell debris from uterine lining lost through vagina

80
Q

menarche

A

Females first menstruation

marks commencement of puberty

81
Q

Menopause

A

occur at 45-55 years old

Menstrual cycle becomes irregular, eventually ceasing

82
Q

secondary sexual characteristics

A

Cause by secretion of sex hormones

anything changes not affecting sexual reproductive organs.

yr.11 Human Biology (10 decks)

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