36 WJEC Biology AS Level - Marianne Izen - 2nd Edition Flashcards
What is present within the stroma of the chloroplast?
Within the stroma are many closed, flattened sacs called thylakoids.
What is a granum?
A stack of thylakoids is a granum.
What is a granum comprised of?
Each granum comprises between two and a hundred parallel sacs.
What is found in the thylakoids?
The photosynthetic pigments, such as chlorophyll, are found in the thylakoids.
What is the significance of the arrangement of thylakoids in the chloroplasts?
This arrangement produces a large surface area, efficient for trapping light energy.
What does electron micrograph show about the thylakoid membrane?
Electron micrographs show that the thylakoid membrane is an infolding of the inner membrane of the
chloroplast envelope.
Draw and label the basic structure of a chloroplast
What does this figure show?
Theory (Key Term)
The best explanation of a phenomenon, taking all the evidence into account.
A theory represents the highest status a scientific concept can have.
What is endosymbiosis?
Endosymbiosis is a theory that describes the origin of chloroplasts and mitochondria.
What did the division of chloroplasts closely resemble?
As far back as 1883, the division of chloroplasts was seen to closely resemble that of free- living cyanobacteria.
What was mitochondria thought to be originally?
In the 1920s, the idea that mitochondria were once independent bacteria was also suggested.
What are the commonalities between mitochondria and chloroplats
Mitochondria and chloroplasts have 70S ribosomes and circular DNA.
What do scientists think happened 1.5 x 10e9 years ago?
It is suggested that at least 1.5 x 10e9 years ago, some ancient bacteria with very fluid membranes engulfed others and maintained a symbiotic relationship with them.
What do we think evolved into mitochondria?
Some of those engulfed bacteria were very good at turning glucose and oxygen into ATP, evolving eventually into mitochondria.
What do we think evolved into chloroplasts?
Some could turn carbon dioxide and water into glucose, evolving eventually into chloroplasts.
What was published in 1967 about endosymbiosis?
In 1967, Lynn Margulis published a paper titled ‘On the origin of mitosing cells’ which substantiated the idea of endosymbiosis.
What do biologists think the origin or chloroplasts and mitochondria are?
Now, biologists have plenty of evidence that both chloroplasts and mitochondria have their origins in free-living prokaryotes.
What is the endoplasmic reticulum?
The endoplasmic reticulum (ER) is an elaborate system of parallel double membranes forming flattened sacs with interconnected, fluid-filled spaces between them, called cisternae.
What is the ER connected to?
The ER is connected with the nuclear envelope.
What does the ER system do?
This system allows the transport of materials through the cell.
What are the types of ER?
There are two types of ER:
Rough ER (RER)
Smooth ER (SER)
What is the structure and function of rough ER?
Rough ER (RER) has ribosomes on the outer surface and transports the proteins made there.
Where is RER present in large amounts?
RER is present in large amounts in cells that make a lot of protein, such as cells making amylase in the salivary glands.
What does smooth ER comprise of?
Smooth ER (SER) comprises membranes that lack ribosomes.
What is the function of smooth ER?
It is associated with the synthesis and transport of lipids.
Which cells have extensive ER?
Cells that store large quantities of carbohydrates, proteins and fats, including liver and secretory cells, have extensive ER.
What does this figure show?
