Topic 2: eukaryotic cells

Question 1

Describe structure and function of cell-surface membrane

Answer 1

Phospholipid bilayer – molecules embed within and attached on the outside (proteins, carbohydrates, cholesterol)

Function
Cell-surface membrane
Controls the entrance and exit of molecules

Question 2

Describe structure and function of nucleus

Answer 2

Nuclear Envelope - double membrane with nuclear pores Nucleoplasm – granular, jelly-like material. Chromosomes – protein-bound, linear DNA. Nucleolus – smaller sphere inside which is the site of rRNA production and makes ribosomes.

Site of DNA replication and transcription (making mRNA)
Contains the genetic code for each cell

Question 3

Describe structure and function of mitochondria

Answer 3

Double membrane with an inner membrane called the cristae The fluid centre called the mitochondrial matrix
Loop of mitochondria DNA

Site of aerobic respiration

Question 4

Describe structure and function of golgi apparatus and golgi vesicles

Answer 4

Folded membranes making cisternae
Secretory vesicles pinch off from the cisternae

Add carbohydrates to proteins to form glycoproteins, produce secretory enzymes, secrete carbohydrates, transport, modify and store lipids and form lysosomes. The molecules are then ‘labelled’ with their destination

Question 5

Describe structure and function of lysosomes

Answer 5

Bags of digestive enzymes – can contain 50 different enzymes.

Hydrolyse phagocytic cells and completely break down dead cells (autolysis). Exocytosis– release enzymes outside the cell to destroy the material. Digest worn-out organelles for reuse of materials

Question 6

Describe structure and function of ribosomes

Answer 6

Small, made up of two sub-units of protein and rRNA.80s-large ribosome found in eukaryotic cells. 70S -smaller ribosome found in prokaryotic cells, mitochondria and chloroplasts.

The site of protein synthesis

Question 7

Describe structure and function of rough and smooth endoplasmic reticulum

Answer 7

Rough and Smooth ER both have folded membranes called cisternae
Rough ER have ribosomes on the cisternae.

RER –Protein Synthesis
SER –Synthesis and store lipids and carbohydrates

Question 8

Describe structure and function of cell wall

Answer 8

In plants and fungi cells. Plants- made of microfibrils of the cellulose polymer. Fungi -made of chitin, a nitrogen- containing polysaccharide

Provides structural strength to the cell

Question 9

Describe structure and function of cell vacuole

Answer 9

Filled with fluid surrounded by a single membrane called a tonoplast.

Makes cells turgid and therefore provides support. Temporary store of sugars and amino acids. The pigments may colour petals to attract pollinators.