Part 3 - Growth Flashcards
Define the term ‘hormone’
A signalling molecule within a multicellular organism; effectively hormones deliver messages between cells
Define the term arthropod?
A phylum of the animal kingdom
They do not have a backbone (invertebrate)
They have a skeleton on the outside of the body (exoskeleton)
A segmented body with jointed legs and are symmetrical along their length
Give some examples of Arthropods
Insects (butterflies, ants etc)
Arachnids (spiders, mites, scorpions)
Chilopods (centipedes)
Diplopoda (millipedes)
What are the three processes involved with growth?
Cell division
Synthesis of new structures from raw materials
Cell expansion
What sort of growth pattern do vertebrates show?
Vertebrates tend to start with slow growth, then speed up the rate of growth before slowing down again
What sort of growth pattern do arthropods show?
Arthropods show a stepped growth pattern
What factors determine growth in plants and animals?
External factors include temperature, diet and light . Growth is determined internally by hormones
What are meristems and where are they found?
Meristems are actively dividing cells found in plants at the tip of the roots and shoots
What is secondary growth in plants?
It is the increase in girth
What does an arthropod do when it grows bigger?
It sheds
When a cell divides what are the cells called that are produced?
Progeny cells or daughter cells
What is the difference between the growth of a multicelled organism and a single celled organism?
Multicellular organisms grow in size whereas single celled organisms grow in numbers
Define the term mutation?
A change in the genes of a plant or animal that causes it to become different
What is asexual production?
Only one parent is needed to produce offspring
This is what single celled organisms do
What is sexual reproduction? The
Two parents are required to produce offspring
What is the process that most prokaryotic cells divide?
Binary fission
Reproduction of a cell by division into two approximately equal parts
The process of cell division, binary fission, in prokaryotes is much simpler than the process of cell division in eukaryotes because the cells are simpler.
In what way are prokaryotic cells simpler than eukaryotic cells?
Prokaryotic cells do not have internal organelles
What is meant by the term cell cycle?
It is a series of processes that take place in a cell
How long can a cell cycle of a eukaryote take?
Anywhere from a few hours to many weeks
What factors does the rate at which a cell proceeds through the cycle depend on?
Type of organism
The type of cell
It’s size
Environment in which it is growing
On average how long does it take cells to divide on
A plant
The gut of a mouse
Human skin?
A plant- 12 hours
Gut of a mouse- 17 hours
Human skin- 24 hours
How many phases are there in a eukaryote cell cycle?
4 phases
What are the 4 phases of a eukaryote cell called?
G1 (gap1) phase
S phase (synthesis)
G2 (gap 2) phase
M phase (mitosis)
What are the first three phases of a eukaryote cell cycle collectively known as?
Interphase
What happens in the G1 phase of a eukaryote cell cycle?
The first phase of the cell cycle
The cell grow
Increasing the number of organelles
Prepares for DNA synthesis
What happens in the S phase of a eukaryote cell cycle?
The second phase
The DNA is replicated
By the end of this phase the cell has copied each chromosome
What happens in the G2 phase of a eukaryote cell cycle?
The cell prepares for division in the G2 phase
What happens in the M phase of a eukaryote cell cycle?
It is a relatively short but highly dynamic phase
It is known as mitosis
The chromosomes condense and 2 sets of chromosomes segregate equally into 2 separate nuclei
The cytoplasm divides, to form 2 completely separate daughter cells.
What is cytokinesis?
It is when the cytoplasm of a cell divides during the mitosis phase of a eukaryote
What do cells do when they divide?
They can immediately re enter the cycle and divide again, or they can exit the cycle to a resting phase called G0 where they will remain until stimulated to enter G1 again
What is mitosis?
It is the last phase of cell division for a eukaryote
It involves the two set of chromosomes condensing and then segregating equally into two separate nuclei
How many pairs of chromosomes do humans have ?
23
How many chromosomes do humans have ?
46
23 pairs
What are autosomes?
Any chromosome that is not a sex chromosome
Look similar
What is a sex chromosome?
It is the chromosome that determines whether you are male or female
What is a homologous chromosome?
Pair of chromosomes
That contain hereditary genes one from the mother and one from the father
What are the 5 stages of mitosis?
Prophase Metaphase Anaphase Telophase Cytokinesis
At what stage of the cell cycle does DNA replication occur?
S (synthesis) phase
When does the prophase of mitosis start?
When the chromosome condense prophase starts
At what stage do chromosomes become visible under a microscope
Prophase
The first stage of mitosis
What is a diploid cell?
A cell that contains homologous chromosomes
Pair of chromosomes - one from the mother- one from the father
When a chromosome is replicated in S phase how does it appear?
Each chromosome consist of an identical pair of chromatids connected at the centromere
What happens in the metaphase of mitosis?
At metaphase the chromosomes line up with their centromeres aligned at the equator of the cell
What happens in the anaphase of mitosis?
At anaphase the centromere of each chromosome divides and he two chromatids are drawn towards opposite piles of the cells. The delayed chromatids are now referred to as chromosomes
During anaphase the chromatids are pulled to the outer part of the cell, what is the mechanism that drives the movement of the chromatids
The spindle microtubules to which each chromatid is attached shorten, thereby drawing the chromatid towards the pole
What happens in telophase of mitosis of a cell?
At telophase the spindle disassembles. A new nuclear membrane develops around each of the two groups of chromosomes
What is the final result of mitosis and cytokinesis?
Two diploid cells, each genetically almost identical to the original parent cell
Define the term centromere?
It is the point of attachment of a chromatid
What happens in prophase of mitosis?
Chromosomes condense
2 homologous chromosomes pair
Nuclear membrane breaks down
Spindle microtubules attach to centromere
What is a chromatid?
One of two identical strands into which a chromosome splits during mitosis
What is the mechanism that drives the movement of chromatids?
The spindle microtubules to which each chromatid is attached shorten, thereby drawing the chromatid towards the pole
How do prokaryotic cells divide?
Prokaryotic cells divide (reproduce) asexually by the process of binary fission and this results in reproduction of the parent cell into identical progeny cells
