Cells Flashcards
organelle
a part of a cell with a specialized function
labelled diagram of the cell
algae
informal term for a large and diverse group of photosynthetic eukaryotic organisms
Petri dish
is a shallow transparent lidded dish that biologists use to hold a growth medium in which cells can be cultured, originally, cells of bacteria, fungi and small mosses.
trichocyst
organelle found in certain single-celled eukaryotes
haemoglobin
protein that transports oxygen
eukaryote
cell with a nucleus (and other organelles)
meiosis
one diploid nucleus divides to produce four haploid (genetically different) nuclei; meiosis produces germ (sex) cells (eggs and sperm)
mitosis
division of the nucleus into two genetically identical daughter nuclei, allows the cell to divide into two daughter cells with the same DNA
diploid
having pairs of homologous chromosomes
haploid
haveing only one chromosome of each pair
Explain how the cell cycle is controlled
cladogram
tree diagrams that show the most probable sequence of divergence in clades
clade
group of organisms evolved from a common ancestor is called a clade
Why are cladograms based on DNA sequences more reliable than cladograms based on protein sequences?
several different triplets of DNA can code for the same amino acid
During part of the cell cycle is DNA replciated?
Interphase
Stages of mitosis
- prophase
- metaphase
- anaphase
- telophase
prophase
- chromosomes become shorter and fatter by coiling
- nucleolus breaks down
- microtubules grow from microtubule organizing centres
- nuclear membrane breaks down
metaphase
- microtubules continue to grow and attach to the centromeres
- chromosomes align on metaphase plate
- spindle fibres (one from each pole) attach to opposite sides of each centromere
anaphase
- each centromere divides
- the pairs of sister chromatids separate
- spindle microtubules pull them rapidly towards the poles of the cell
- mitosis produces two genetically identical nuclei because sister chromatids are pulled to opposite poles
telophase
- chromatids have reached
the poles (therefore now called
chromosomes) - at each pole the
chromosomes are pulled into a
tight group - nuclear membrane reforms
around them - chromosomes uncoil
- nucleolus is formed
cytokinesis
formation of new cell membranes around the daughter cells
interphase
- consists of three phases
- Gā
- S
- Gā
- replication of DNA during S phase
- copied chromosomes are called sister chromatids and are bound together at centromere
mitotic spindle
microtubles that connect to centromeres
