Click4Biology: 2.3 Eukaryotic cells

Eukaryotic cells

2.3.1 Diagram of the eukaryotic liver cell.

2.3.2 Functions of the cell parts.

2.3.3 Electron micrographs of the liver cell.

2.3.4 Compare the prokaryotic and eukaryotic cell.

2.3.5 Three differences between a plant and an animal cell.

2.3.6 Outline two roles of extracellular components.

 

2.3.1.Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell (1).

 

Draw: To represent by means of pencil lines.

 

see 2.3.2 form functions of the cell components.

 

 

2.3.2 Annotate the diagram from 2.3.1 with the functions of each named structure.

Annotate: to add brief notes to a diagram or graph.

Nucleus: This is the largest of the organelles. The nucleus contains the chromosomes which during interphase are to be found the nucleolus.

nucleus

 

 

 

Plasma membrane: controls which substances can enter and exit a cell. It is a fluid structure that can radically change shape. see 2.4

 

 

 

 

 

Mitochondria: location of aerobic respiration and a majot synthesis of ATP region..

mito

 

 

 

 

Rough endoplasmic reticulum (rER): protein synthesis and packaging into vesicles.

rER

 

 

Ribosomes: the free ribosome produces proteins for internal use within the cell.

 

 

 

 

 

 

 

 

Golgi apparatus: modification of proteins prior to secretion.

 

 

 

 

 

Lysozyme:

 

 

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2.3.3 Identify structures from 2.3.1 in electron micrographs of liver cells.(2)

Identify: To find an answer from a given number of possibilities.

To identify structures within an electron micrograph it is necessary to know the scale at which the image has been taken. Look around the image to find the nucleus and then the mitochondria. In a plant cell there will also be the cell wall, chloroplasts and the vacuole to identify.

 

Nucleus:

nucleus

In an electron micrograph the nucleus will be the largest of the organelles.

In this image there is a dark stained region called the nucleolus which is the location of the DNA.

The membrane has pores which allow the entry of cell signal molecules, nucleotides and the exit of mRNA.

Generally the nucleus appears spherical however there are cells in which the nucleus has more unusual shape such as the multi-lobbed white blood cells.

 

 

 

 

Plasma membrane:

 

This image shows the junction between two liver cells. The image has been manipulated for clarity to see the two adjoining plasma membranes.

Notice the mitochondria to the left and the rER to the right of the membranes.

 

 

 

 

 

Mitochondria:

This micrograph of a mitochondria shows:

These features are common to all mitochondria. Notice the rER above the mitochondria for scale and the dark granules of glycogen below the organelle.

 

 

 

 

Endoplasmic reticulum (rER).

rER

 

 

 

Golgi apparatus:

 

 

 

 

 

Lysosome:

Boston University Histology this site is a great source of histological diagram including those of the liver cell (syllabus specified).

 

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2.3.4 Comparison of prokaryotic and eukaryotic cells (3).

compare means to give an account of similarities and differences between two (or more) items, referring to both (all) of them throughout.

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2.3.5 State three differences between plant and animal cells (1).

State:means to give a specific name, value or other brief answer without explanation or calculation.

Only three differences from this list are required.

 

Plant cell electron micrographs and images are provided at this stage although not specified at this point in the syllabus

Chloroplast:

chloroplast Note:

double membrane

internal thylakoid membranes which contain the chlorophyll.

Stroma where the calvin cycle fixes CO2 into carbohydrates, oils or starch.

 

 

 

 

Vacuole:

The vacuole is a storage area for organic solute such as sugars and amino acids.

The vacuole is surrounded by a membrane called the tonoplast which has essentially the same type of structure as the plasma membrane.

 

 

 

 

 

 

 

Cell Wall:

Plant cell walls are composed of cellulose (2.3.6)

In the electron micrograph we can see cytoplasmic connections through adjacent cells. These are called plasmodesmata.

 

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2.3.6 Outline two roles of extracellular components(3).

Outline means to give a brief account or summary.

a) Plant cell wall.

 




b) Animal extracellular matrix

i) Basement membrane: a secretion formed from collagen and glycoproteins joined together by a third 'linkage' protein. Their exact composition varies form tissue to tissue.

Support: the membrane surrounds the tissues of lines ducts. It provides structural support for the integrity of the tissue or organ. Usually found as the basal lamina or basement membrane of epithelial cells.

Filter : The basement membrane of the kidney glomerulus provides the effective barrier for ultrafiltration

Vascular niche : Interestingly cells often require a base on which to organise before they will form proper tissue. There are implications here for developmental biology, tissue repair, stem cell therapies and cancer treatment.

ii) Interstitial matrix:

 

Bone has a matrix which includes collagen with a calcium phosphate.

Other tissues are surrounded by a matrix composed of a kind of gel that provides support for the tissue.

 

 

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