Cell Structure and Division-Topic 2A Flashcards
Why are cells grouped into tissues, and organs into organ systems?
For increased efficiency.
Define a tissue.
A collection of similar specialised cells that perform a specific function.
Define an organ.
A combination of tissues that are coordinated to perform a variety of functions (often 1 predominant function).
What is an organ system?
A group of organs working together to perform particular functions more efficiently.
What is the difference between a tissue and an organ?
Organs consist of different types of tissue, not just one e.g. connective and epithelial.
Where is the cell surface membrane usually found?
On the surface of animal cells.
Where else can the cell surface membrane be found?
Inside the cell wall of OTHER cells.
What does the cell-surface membrane consist of?
Lipids and protein.
What is the function of the cell-surface membrane?
To regulate the movement of substances into and out of the cell.
Has receptor cells so it can respond to hormones.
Describe the nucleus
Large organelle, surrounded by nuclear envelope (double membrane) containing many pores.
Contains chromosomes and nucleolus.
What is the function of the nucleus?
Controls cell’s activities .
DNA has instructions to make proteins
Pores allow substances to move between nucleus and cytoplasm e.g. RNA
Nucleolus makes ribosomes.
Describe mitochondrion
Double membrane (inner folded in cristae) Inside is the matrix containing enzymes for respiration.
What is the function of mitochondria?
Site for aerobic respiration (ATP produced here)
therefore they are found in large numbers in very active cells that require lots of energy.
Describe a chloroplast
Flattened structure in plant and algal cells. Surrounded by double membrane.
What is the function of chloroplasts?
Site where photosynthesis takes place (some parts happen in grana, others in stroma)
Describe Golgi apparatus
A group of fluid filled, membrane-bound sacs.
Vesicles often @ edges of the sacs.
Function of Golgi apparatus?
Modifies triglycerides
Processes and packages new lipids and proteins.
Makes lysosomes.
What 3 organelles are in plant cells but not animal cells?
Vacuoles
Chloroplasts
Cellulose cell wall (with plasmodesmata)
How do fungal cells differ from plant cells?
Cell walls are made of chitin (not cellulose)
DON’T have chloroplasts (because they don’t photosynthesise)
Which cell is plasmodesmata in and what does it do?
Plant cells
Plasmodesmata is a channel for exchanging substances with adjacent cells.
What does a vacuole do?
Contains cell sap, it maintains pressure in thee cell and keeps it rigid-stops plant wilting
What type of cell has the same organelles as a plant cell?
An algal cell
How do prokaryotic cells replicate?
Binary Fission
Viruses are… they are not cells
Viruses are acellular. They are not cells.
What are viruses made up of?
Nucleic acids surrounded by protein. They are not living.
Name 3 parts of a virus
core of genetic material
protein coat- capsule
Attachment proteins
All viruses …… and ……… inside cells of other organisms. These cells are known as …….
All viruses invade and reproduce inside cells of other organisms. These cells are known as host cells.
Name the two organelles that aren’t membrane bound in Eukaryotic cells
Ribosomes and centrioles.
What is “processed data”?
Calculations made (from raw data)
List the organelles always present in Eukaryotic cells
Cell surface membrane
Ribosomes
Nucleic acids
Mitochondria
List the organelles sometimes in Eukaryotic cells
Chloroplasts
Cell wall
Vacuole
List the organelles always in prokaryotic cells
Cell-surface membrane
Ribosomes
Plasmid
Nucleic acid
Why are tissues homogenised?
To break open cells AND remove debris
Why is the homogenised tissue kept cold?
To slow down enzyme activity.
Why is the homogenised tissue kept in an isotonic solution
To prevent damage to the cell through osmosis.
Why is the homogenised tissue kept in a buffered solution?
To maintain the pH as any change in pH can alter the structure of the enzyme or the functioning of the enzyme.
What is mitosis?
Cell division that produces Genetically Identical Cells
What is mitosis needed for?
The growth of multicellular organisms
And repairing damaged tissues
What is the period of cell growth and DNA replication?
Interphase
Name the 3 stages Interphase is subdivided into
G1, S and G2
What does mitosis produce?
Two genetically identical daughter cells (containing an exact copy of the DNA of the parent cell)
How many stages is Mitosis split into? Name them
4 Prophase Metaphase Anaphase Telophase
Name the phases before and after mitosis
Gap phase 2( G2 is before) Cell keeps growing and proteins needed for cell division are made
Mitosis
Gap phase 1 (G1 is after) Cell grows. New organelles and proteins are made.
Besides the phases immediately before and after mitosis, name the other phase.
Synthesis (after G1)
Name the 3 phases of interphase
G2, G1, Synthesis
What stage of interphase is the longest? What happens in this stage?
Synthesis: Cell replicates its DNA ready to divide by mitosis.
Describe what happens at interphase?
DNA unravelled and replicated
ATP content increases
Organelles replicated
Describes what happens at Prophase?
Chromosomes condense (get shorter and fatter) Centrioles move to opposite ends of cell forming protein fibres called spindle fibres Nuclear envelope breaks down
Describe what happens are Metaphase
The chromosomes (each with 2 chromatids) line up along the middle of the cell.
These attach to spindle by their centromere
Anaphase
Centromeres divide, separating each pair of sister chromatids.
Spindles contract, pulling chromatids to opposite poles of the spindle. (Appear V shaped)
Telophase
Chromatids reach opposite poles on the spindle.
Nuclear envelope reforms
Cytoplasm divides (cytokinesis) = two genetically identical daughter cells.
Cancer is the result of …….. …. ……..
Cancer is the result of uncontrolled cell division
What are mitosis and the cell cycle controlled by?
Genes
If there is a mutation in the gene controlling cell division, what is likely to happen?
The cells can grow out of control
What is cancer?
A tumour that invades surrounding tissue
Some Cancer treatments target….
Some cancer treatments target the cell cycle.
Some cell cycle targets of cancer treatments include:
G1- Cell growth and protein production.
Some chemical drugs (chemotherapy) prevents synthesis of enzymes- this makes cell unable to enter the synthesis phase therefore killing itself
S phase- radiation damages DNA, if sever damage then cell will kill itself preventing further tumour growth.
Cells will generally divide when …….
they become too large
What is different about the division of cancer cells?
If there is a mutation in a gene controlling cell division the cells grow out of control.
Give the 2 main functions of mitosis
Growth
Repairing damaged tissue
Describe how tumours are formed
Mutation in gene leads to uncontrolled cell division and the cells which keep on dividing forming a tumour
Out of starch grains, double outer membranes and diffusion of oxygen into the organelle- which features relate to mitochondria/chloroplasts or both?
Mitochondria: double membrane, diffusion of oxygen
Chloroplasts: double membrane, starch grains.
Name two structures in a eukaryotic cell that cannot be identified using an optical microscope
Lysosomes
Ribosomes
Name the polymer that makes up a prokaryotic cell wall. What is it an example of?
Murein which is a glycoprotein.
Name organelles SOME prokaryotes have.
Flagellum
Plasmid
Capsule
Name organelles ALL prokaryotes have.
Cell wall
Plasma membrane
Free floating circular DNA
Cytoplasm, with ribosomes.
In binary fission the cell ….. its …….. ……. before splitting into two ….. ………….
In binary fission the cell replicates its genetic material before splitting into two daughter cells.
Why should you push down hard on the cover slip, but not push the cover slip sideways?
To squash the tissue sample.
Not sideways to avoid breaking chromosomes.
Why are cells taken from a root tip?
This is the region where mitosis occurs.
Why is the root tip firmly squashed?
To allow light through/ make tissue layer thin.
During meiosis what is the reason for the first decrease in DNA per cell?
Homologous chromosomes separate.
During meiosis what is the reason for the second decrease in DNA per cell?
Sister chromatids separate.
Name plant organelles from heaviest to lightest (for ultracentrifugation)
Nuclei-(chloroplasts if plant cell)-mitochondria-lysosomes-endoplasmic reticulum-ribosomes
