Euk and prok cell features and functions

Question 1

Where is the DNA found in a eukaryotic cell?

Answer 1

Enclosed in a membrane bound nucleus

Question 2

What are chromosomes formed by?

Answer 2

DNA tightly wrapped around by proteins called histones, together this forms chromosomes

Question 3

Give the main characteristic of the DNA in a eukaryotic cell

Answer 3

The DNA is linear meaning that the ends of the DNA molecule in the chromosome is not coiled to form a loop

Question 4

Name the membrane bound organelles in a eukaryotic cell

Answer 4

Mitochondria, golgi apparatus, and the endoplasmic recticulum. in plant cells chloroplast and vacuole is also membrane bound.

Question 5

Name the organelles in a eukaryotic cell that are not membrane bound

Answer 5

Ribsomes

Question 6

Give the different types of ribosomes found in cells

Answer 6

80s ribosomes found in eukaryotic cells
70s ribosomes found in prokaryotic cells which is smaller

Question 7

Give the function of the cell surface membrane, and what type of cell has this

Answer 7

Helps control the molecules that pass in and out of a cell in animal cells, plant cells have this surrounded by a cell wall.

Question 8

What is the cell wall in plant cells made from?

Answer 8

Polysaccharide cellulose

Question 9

Give 3 uses of proteins

Answer 9

Enzymes for chemical reactions, Structural proteins e.g organelle movement and transport molecules e.g heamoglobin
This means protein synthesis is one of the most important processes that takes place in cells.

Question 10

Describe the role of the nucleus in protein synthesis

Answer 10

The instructions for encoding the amino acid sequence of a protein are contained within the gene for that protein. These genes are made up into chromosomes which are found in the nucleus.
- When a protein is being synthesised, the genetic information encoded by that gene is converted into mRNA which is called transcription
- This mRNA then leaves the nucleus, and a ribosome reads the information contained and then synthesises the protein molecule, which is called translation.
- If a protein remains in the cytoplasm, translation will take place on a free ribosome in the cytoplasm, however some are secreted by cells so they make their way through the rough ER and the golgi apparatus before leaving the cell.

Question 11

What is the nucleoplasm?

Answer 11

A material in the nucleus containing nucleotides and enzymes, which is needed for DNA and RNA synthesis.

Question 12

What is the function of nuclear pores?

Answer 12

Found in the nuclear envelope, these allow passage of large molecules and allows molecules to enter and leave the nucleus.

Question 13

What is the nuclear envelope?

Answer 13

The double membrane on the outside of the nucleus which contains 2 phospholipid bilayers

Question 14

Give the characteristic of the outer membrane of the nuclear envelope

Answer 14

This is continuous with the rough endoplasmic reticulum, forming flattened sacs called cisternae.

Question 15

Describe the function of the RER

Answer 15

Has a large surface area with ribosomes present on the outer surface for synthesising proteins and is a pathway of transport.

Question 16

What is a chromatin?

Answer 16

Found in the nucleus, these consist of DNA coiled around proteins called histones, these paired together create chromosomes.

Question 17

When can we see chromosomes in a nucleus?

Answer 17

Only when the cell is undergoing mitosis or meiosis

Question 18

What is the function of the nucleolus?

Answer 18

Found in the nucleus, special types of RNA is formed called rRNA, and ribosomal subunits are assembled.

Question 19

Give the 2 key features of lysosomes

Answer 19

They contain powerful digestive enzymes such as proteases, which digest large molecules into smaller soluble molecules
They also have an acidic internal fluid because lysosomal enzymes have an optimum PH of acidic

Question 20

Give the functions of lysosomes

Answer 20

They play a key role in phagocytosis, when a WBC forms a vacuole around a bacteria, called a phagosome, lysosomes will now fuse with this and the lysosomal enzymes will digest the bacteria.
-They also can destroy organelles that are damaged or no longer functional. This happens when the organelle is wrapped in a vacuole so the vacuole fuses to the membrane and uses its enzymes to digest the organelle.
- Lysosomes can also transfer their enzymes to out of the cell in exocytosis to digest and remove unwanted proteins or dead cells.

Question 21

Describe the structure of a mitochondria

Answer 21

A double membrane with inter-membrane space. Has a fluid called the matrix where enzymes for the Krebs cycle are found.
- There is also a loop of DNA there containing the genes needed for enzymes found in mitochondrial respiration
- There are also mitochondrial l ribsomes which synthesise proteins encoded by mitochondrial DNA.

Question 22

Give an adaptation of mitochondria

Answer 22

They have large amounts of cristae which provide a large surface area for enzymes needed for oxidation phosphloryiation.