Structure of eukaryotic cells Flashcards
Nuclear envelope
Is a double membrane that surrounds the nucleus. It controls the entry and exit of material in and out of the nucleus and contains the reactions taking place within it.
Nuclear pores
Allow the passage of large molecules such as messengers RNA out of the nucleus
Nucleolus
Is a small spherical region within the nucleoplasm. It manufactures ribosomal RNA and assembles the ribosomes
Mitochondria
The site of aerobic stages of respiration (ATP) which is made up of a double membrane which controls the entry and exit of materials
Cristae
Are extensions of the inner membrane which in some species extend across the whole width of the mitochondrion. These provide a large surface area for the attachment of enzymes
Matrix
Makes up the remainder of the mitochondrion. It contains proteins, lipids, ribosomes and DNA that allows the mitochondrion to control the production of their own proteins.
Grana
Stacks of up to 100 disc-like structures called thylakoids, within the thylakoids is the photosynthetic pigment chlorophyll. This is where the first stage of photosynthesis occurs
Stroma
A fluid-filled matrix where the second stage of photosynthesis takes place
Golgi apparatus
responsible for transporting, modifying and packaging proteins and lipids into vesicles for delivery to targeted destinations.
functions of golgi apparatus
-add carbohydrates to proteins to form glycoproteins
-produce secretory enzymes, such as those secreted by the pancreas
-secrete carbohydrates such as those used in the making cell walls in plants
-transport, modify nba dpackage lipids
-form lysosomes
Lysosomes
Are formed when the vesicles produced by the golgi apparatus contain enzymes such as protease and lipase. They also contain lysozymes enzymes that hydrolyse the cell wall of certain bacteria.
Rough endoplasmic reticulum
Has ribosomes present on the outer surfaces of the membranes
- Provides a large surface area for the synthesise of proteins and glycoproteins
- Provide a pathway for the transport of materials, especially proteins throughout the cell
Smooth endoplasmic reticulum
Lacks ribosomes on its surface
- synthesises, stores and transports lipids
- synthesises, stores and transports carbohydrates
Ribosomes
Small cytoplasmic granules, 80s found in eukaryotic cells, occur in vast numbers (Cytoplasm)
-site of protein synthesis
Cell wall
-Characteristic of plant cells
Consists of microfibrils of polysaccharide cellulose, embedded in matrix.
-microfibrils have considerable strength so contribute to the overall strength of the cell wall
Specialised cell
a specialised cell have a specific feature to carry out a particular role
Differentiation
The process of when unspecialised cells (stem cells) turn into specialised cells
Tissue
Many identical specialised cells come together to perform a specific function
Organ
A group of tissues that are coordinated to perform a function
Organ system
A group of organs that perform a particular function more efficiently
Multicellular organism
Organisms that are made up of multiple cells
Eukaryotic cell
are larger and have a nucleus bounded by nuclear membranes
Chitin
Found in the cell wall of fungi
Histone
A protein that provides structural support for each chromosome
Structure of eukaryote
-Distinct nucleus with nuclear envelope
-DNA is associated with proteins called histone
-No plasmids +DNA is linear
-Membrane bound organelles (mitochondria)
-Chloroplasts present in plant +fungi
-Ribosomes are larger (80s)
The nucleus
Contains the organism’s hereditary material and controls the cell’s activities
Nucleoplasm
Is the granular, jelly like material that makes up the bulk of the nucleus
Chromosomes
consist of protein-bound linear DNA
what are the parts that make up the nucleus
Nuclear envelope, nuclear pores, nucleoplasm, chromosomes and the nucleolus
Describe the structure and function of the nucleus.
Structure:
Nuclear envelope and pores/ Double membrane and pores;
2. Chromosomes/ DNA with histones;
3. Nucleolus/nucleoli;
Function:
4. (Holds/stores) genetic information/material
for polypeptides (production)
5. DNA replication (occurs);
6.Transcription (occurs);
7. Production of rRNA/ribosomes;
Chloroplasts
organelles that carry out photosynthesis
Chloroplast envelope
A double plasma membrane that surrounds the organelle and is highly selective in what it allows to enter and leave
How are chloroplasts adapted to carry out photosynthesis
-the granal membranes provide a large surface area for the attachment of chlorophyll, electron carriers and enzymes in the first stage of photosynthesis
-The fluid of the stroma possesses all the enzymes needed to make sugars in the second stage of photosynthesis
-Contain both DNA and ribosomes so they can quickly and easily manufacture some of the proteins needed for photosynthesis
What is the endoplasmic reticulum
An elaborate three dimensional system of sheet like membranes spreading through the cytoplasm of the cells. It’s continuous with the outer nuclear membrane and enclose a network of tubules and flattened sacs
What are the two types of endoplasmic reticulum
Rough endoplasmic reticulum
smooth endoplasmic reticulum
What is the function of lysosomes
-hydrolyse material ingested by phagocytic cells
-release enzymes to the outside of the cell in order to destroy material around the cell
-digest worn out organelles so that useful chemicals they are made up of can be re-used
-completely break down cells after they have died
What are ribosomes made up of
-ribosomal RNA
-protein
What is the function of the cell wall
- to provide mechanical strength in order to prevent the cell bursting under the pressure created by the osmatic entry of water
-to allow water to pass along it and so contribute to the movement of water through the plant
Vacuole
A fluid filled sac bound by a single membrane
-In a mature plant cell there is usually one large central vacuole
-contains a solution of mineral salts, amino acids and sugars
What is the function of the vacuole
-Temporary food store
-The pigment may colour petals to attract pollinating insects
-Support herbaceous parts of woody plants
