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A2 Chapter 1 > 1.4 > Flashcards

1.4 Flashcards

0
Q

Follicle cells secrete

A

Chemicals that activate the release of enzymes from sperm

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1
Q

6 Parts of an ovum

A 
Nucleus 
Follicle cells
Cytoplasm 
Lipid droplets
Zona pellucida
Lysosomes
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2
Q

(Ovum) Cytoplasm is very large so

A

The egg can divide immediately

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3
Q

(Ovum) lipid droplets are the

A

Source of energy for growth and division for the developing embryo until the placenta has formed

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4
Q

(Ovum) zona pellucida hardens once the sperm nucleus has

A

entered the ovum, this stops the entry of other sperms into the ovum (avoids polyspermy)

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5
Q

(Ovum) lysosomes release chemicals that

A

Cause zona pellucida to harden

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6
Q

5 Parts of the sperm:

A 
Nucleus
Head
Mid piece
Tail (flagellum)
Acrosome
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7
Q

(sperm) head contains the

A

Nucleus and the lysosomes (Acrosome)

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8
Q

(sperm) mid piece contains…

A

Lots of mitochondria which makes ATP for the sperms to swim

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9
Q

(sperm) the flagellum is made from proteins and micro tubules, which

A

uses ATP to propel the sperm forwards

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10
Q

(sperm) the Acrosome is a specially modified lysosome in the sperm’s head
The Acrosome swells and bursts when the sperm comes in contact with the follicle cells and zona pellucida

The enzymes in the Acrosome digest

A

The follicle cells and zona pellucida to allow the cell membrane of the sperm and ovum to fuse

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11
Q

During copulation the spongy tissues in the penis become swollen with blood making it hard and erect this:

A

Makes it easier to enter the vagina

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12
Q

Semen is ejaculated from the penis and released at the end of the vagina close to the cervix and is:

A

Alkaline to neutralise the acidity of the vagina

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13
Q

The sperm use their flagella to swim through the mucus in the cervix and towards the oviduct, usually takes between 3-5 hours and

A

Contractions of the uterine muscles are thought to help the sperm reach the oviduct

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14
Q

Capacitation are the changes that occur in the sperm along the fertilising tract to

A

Enable them to fertilise the oocyte

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15
Q

Capacitation involves the

A

Removal of cholesterol and some glycoproteins from the membrane above the Acrosome

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16
Q

(CAPACITATION) the removal of cholesterol and glycoproteins makes the membrane

A

More fluid and more permeable to calcium ions

17
Q

The Acrosome reaction must take place before the

A

Sperm can fertilise the oocyte

18
Q

The Acrosome reaction involves the Acrosome releasing the enzymes that help the sperm to digest it’s way through the

A

Zona pellucida

19
Q

Stage 1 AR) the sperm head binds to the jelly coat - this triggers the entry of

A

Calcium ions into the sperm head

20
Q

Stage 2 of AR) the outer membrane of the sperm fuses with the membrane surrounding the Acrosome. This allows the Acrosome to

A

Release enzymes that digest a pathway through the zona pellucida

21
Q

Stage 3 of the AR) the sperm membrane fuses with the plasma membrane of the oocyte - allowing the sperm nucleus to

A

Enter the oocyte

22
Q

When the successful sperm digests it’s way through the jelly coat, the sperm membrane fuses with the oocyte membrane, allowing the

A

Nucleus of the sperm to enter the oocyte

23
Q

As the sperm membrane fuses with the oocyte this causes vesicles in the oocyte called cortical granules to fuse with the oocyte membrane and release their contents into the space between the oocyte membrane and the jelly coat - known as the

A

Cortical reaction

24
Q

The cortical reaction changes the zona pellucida which forms a

A

Fertilisation membrane that prevents the entry of more sperm

25
Q

Stage 1 of fertilisation)

A

Acrosome reaction occurs

26
Q

Stage 2 of fertilisation) the enzymes have enabled the sperm to penetrate the jelly coat. The sperm membrane fuses with the

A

Plasma membrane of the oocyte

27
Q

Stage 3 of fertilisation) the sperm nucleus enters the oocyte and the cortical reaction occurs

A

Cortical granules are released by the oocyte that change the structure of the ZP

  • no more sperm can enter the oocyte
  • oocyte undergoes the second division of meiosis
28
Q

Stage 4 of fertilisation) the male and female nuclei fuse, forming a

A

Diploid zygote

29
Q

Stage 5 of fertilisation) a spindle forms and the zygote divides by

A

Mitosis

30
Q

The fertilised egg becomes a

A

Zygote

-diploid cell

31
Q

As the zygote travels along the oviduct it divides by

A

Mitosis

32
Q

After 3-4 days it has formed a ball or cells known as a

A

Morula

33
Q

About 5-6 days it has formed a

A

Blastocyst

-hollow ball of cells

34
Q

Outer layer of blastocyst =

A

Trophoblast

35
Q

Trophoblast will develop into

A

The membranes around the embryo and the beginnings of the placenta

36
Q

The inner cell mass is the part of the blastocyst from which the

A

Embryo will develop

37
Q

The blastocyst reaches the uterus about a week after fertilisation it takes a few days for it to

A

Implant into the endometrium

38
Q

(Implantation) The zona pellucida surrounding the blastocyst break soon at the trophoblast cells at one end of the embryo form

A

Branched extensions called villi that secrete enzymes

39
Q

(Implantation) these enzymes digest the outer layer of the endometrium,

A

Releasing nutrients for the developing embryo

A2 Chapter 1 (10 decks)

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