Cell Structure and Division-Topic 2A Flashcards by Talia Phillips

Why are cells grouped into tissues, and organs into organ systems?

For increased efficiency.

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Define a tissue.

A collection of similar specialised cells that perform a specific function.

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Define an organ.

A combination of tissues that are coordinated to perform a variety of functions (often 1 predominant function).

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What is an organ system?

A group of organs working together to perform particular functions more efficiently.

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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.

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Where is the cell surface membrane usually found?

On the surface of animal cells.

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Where else can the cell surface membrane be found?

Inside the cell wall of OTHER cells.

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What does the cell-surface membrane consist of?

Lipids and protein.

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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.

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Describe the nucleus

Large organelle, surrounded by nuclear envelope (double membrane) containing many pores.
Contains chromosomes and nucleolus.

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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.

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Describe mitochondrion

Double membrane (inner folded in cristae)
Inside is the matrix containing enzymes for respiration.

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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.

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Describe a chloroplast

Flattened structure in plant and algal cells. Surrounded by double membrane.

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What is the function of chloroplasts?

Site where photosynthesis takes place (some parts happen in grana, others in stroma)

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Describe Golgi apparatus

A group of fluid filled, membrane-bound sacs.

Vesicles often @ edges of the sacs.

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Function of Golgi apparatus?

Modifies triglycerides
Processes and packages new lipids and proteins.
Makes lysosomes.

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What 3 organelles are in plant cells but not animal cells?

Vacuoles
Chloroplasts
Cellulose cell wall (with plasmodesmata)

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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)

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Which cell is plasmodesmata in and what does it do?

Plant cells

Plasmodesmata is a channel for exchanging substances with adjacent cells.

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What does a vacuole do?

Contains cell sap, it maintains pressure in thee cell and keeps it rigid-stops plant wilting

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What type of cell has the same organelles as a plant cell?

An algal cell

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How do prokaryotic cells replicate?

Binary Fission

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Viruses are… they are not cells

Viruses are acellular. They are not cells.

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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