Topic 2 Part 3 - Growth Flashcards
What are the three processes involved in growth?
Cell division, synthesis of new structures from raw materials and cell expansion.
What is an Arthropod?
Any invertebrate animal that, characteristically, possesses an outer body layer—the cuticle—that functions as a rigid protective exoskeleton; growth is thus possible only by periodic moults
What is an exoskeleton?
A rigid external covering for the body in certain animals, such as the hard chitinous cuticle of arthropods. The cuticle of arthropods must be shed at intervals to allow growth to occur
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 tips of roots and shoots.
According to convention should the x-axis be the dependent or independent variable?
Dependent
According to convention should the y-axis be the dependent or independent variable?
Independent
How do cells grow?
They follow a sequence: division and growth
How many cells does each cell produce in each sequence of growth when it divides?
two progeny cells
What positive impact does the cell growth sequence have?
the replenishment of worn-out cells as well as the overall growth of a multicellular organism.
Does multicellular organisms grow as individuals within a population or grow in terms of numbers of individuals within a population?
multicellular organisms grow as individuals within a population
Does single-celled organisms grow as individuals within a population or grow in terms of numbers of individuals within a population?
grow in terms of numbers of individuals within a population.
What is it called when the reproduction of chromosomes are not accurate?
a mutation
How must single cells reproduce?
They must reproduce with themselves (asexual)
What is the term for reproducing with yourself?
asexual reproduction
What is asexual reproduction?
When only one parent is needed to produce two offspring
What is sexual reproduction?
two parents are required to produce offspring
What is the term for the process most prokaryotic divide by?
binary fission
In what way are prokaryotic cells simpler than eukaryotic cells?
Prokaryotic cells do not have internal organelles.
How does cell copying happen in prokaryotic cells?
Replication (copying) of the chromosome starts at one point on the chromosome, known as the ‘origin of replication’ and moves in both directions around the circular chromosome. The end result is a new, copied chromosome and an original chromosome, both of which move to opposite ends of the cell as the cell elongates. The cell then splits down the middle creating two daughter cells, each containing an identical chromosome.
What does the division of eukaryotic cells occur within?
it occurs within a cell cycle which is a series of processes that take place in a cell
How long can cell division take in eukaryotic cells?
can take anything from a few hours to many weeks
What are the four main phases for eukaryotic cells dividing?
G1 (gap 1) phase
S (synthesis) phase
G2 (gap 2) phase
M (mitosis and cytokinesis) phase.
G1, S and G2 are collectively known as what?
interphase.
What happens in G1?
In G1, the first phase of the cell cycle, the cell grows, increasing the number of organelles, and prepares for DNA synthesis.
What happens in the S phase?
In S phase, the DNA is replicated. By the end of this phase, the cell has copied each chromosome.
What happens in the G2 Phase?
The cell prepares for division in the G2 phase, the last stage of interphase.
What is the final phase of eukaryotic cells dividing?
The final phase is the M stage
What happens in the M Phase?
the final stage of the cell cycle, known as the M phase, is relatively short but highly dynamic and consists of two processes. In the first process, known as mitosis, the two sets of chromosomes condense and segregate equally into two separate nuclei. In the second process, known as cytokinesis, the cytoplasm of the cell divides to form two completely separate daughter cells
What are the steps a cell can take after it has gone over its cycle? (Eukaryotic)
Cells 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 G0?
The G0, or resting, phase can be long or short dependent upon the cell type.
What is mitosis
Mitosis is the dynamic phase in the cell cycle. In this phase, the chromosomes condense into two sets, and the two sets of chromosomes segregate equally into two separate nuclei.
What is cytokinesis
Cytokinesis is the physical process of cell division, which divides the cytoplasm of a parental cell into two daughter cells
How many chromosomes does a human cell have?
a human cell has 23 pairs of chromosomes, making a total set of 46 chromosomes
What is autosomes?
The 22 chromosomes that look similar to each other
what is sex chromosomes
The chromosomes in the 23rd pair can appear different from each other - they determine whether humans are male or female.
What is the Prophase?
Prophase is the first phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells.
What is the metaphase
Metaphase is the third phase of mitosis, the process that separates duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells
At what stage of the cell cycle does DNA replication occur?
S Phase
What happens during the prophase
The nuclear membrane breaks down and the spindle microtubules assemble. Spindle microtubules from opposite poles of the cell attach to the centromere of each chromosome.
What happens during the metaphase
At metaphase the chromosomes line up with their centromeres aligned at the equator of the cell.
What is anaphase?
Anaphase is the fourth phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells
What happens during the anaphase?
At anaphase the centromere of each chromosome divides and the two chromatids are drawn towards opposite poles of the cell. The separated chromatids are now referred to as chromosomes.
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 is the telophase?
Telophase is the fifth and final phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells.
What happens during the telophase?
At telophase the spindle disassembles. A new nuclear membrane develops around each of the two groups of chromosomes.
What happens during the cytokinesis phase?
Constriction of the contractile ring forms a cleavage furrow which eventually separates the daughter cells.
What is the final result of mitosis and cytokinesis
The final result of mitosis and cytokinesis is two diploid cells, each genetically almost identical to the original parent cell.
What is the point of attachment called whilst DNA is copying itself?
centromere
What is each newly copied DNA molecule called?
chromatid
What is the earliest phrase in mitosis in eukaryotic cells?
prophase
