Cell structure and division Flashcards
what is a cell?
a cell is the smallest living structural and functional unit of an animals’ body
what is the cell membrane?
- external boundary of the cell
- confines the cell content
- regulates entry and exit of materials
- contains a bilayer of phospholipid
- outer surface is hydrophilic
- inner surface is hydrophobic
what is the cytoplasm?
- consists of cytosol which is a thick fluid
- contains cytoskeleton (made up of tubules and filaments to support and give cell shape)
what is the nucleus?
- centre of the cell - controls the cell
- has perforated membrane called the nuclear envelope (Allows passage of RNA)
- contains genetic membrane in the form of DNA and RNA
what does DNA stand for and what is it?
- deoxyribonucleic acid
- two polynucleotide chains that coil around eachother in a double helix carrying genetic instructions for the development, functioning, growth, and reproduction
what does RNA stand for?
ribonucleic acid
what are ribosomes?
- tiny granules of RNA
- synthesises proteins from amino acid using RNA
- can be in the cytoplasm or attached to the RER
What is the smooth endoplasmic reticulum?
- ER
- folded membranes usually attached to the nucleus
- produce and transport lipids and steroids
what is the rough endoplasmic reticulum?
- stores newly synthesised protein molecules and packages material to be secreted from the cell
- has ribosomes
what is the golgi apparatus?
- processes and sorts packages and delivers proteins and lipids to the plasma membrane
- proteins move from the ER to the golgi via transport vesticles
what are the lysosomes?
- secretory vesicles formed by the golgi
- contain enzymes involved in breaking down damaged organelle and dead cells
- digesting materials
what is phagocytosis?
the process by which cells engulf solid particles
what is pinocytosis?
the process of engulfing fluids
what is the mitochondria?
- the powerhouse of the cell
- where energy is produced and stored
- outer membrane is smooth and the inner is called cristae
what is the equation for cellular respiration?
glucose + oxygen = energy + water + carbon dioxide
what is energy stored and converted into whilst in the mitochondria?
stored as Adenosine Tri-Phosphate and converted into Adenosine Bi-Phosphate
what is the centrosome?
- found near the nucleus of the cell
- appears as cytoplasmic material and radiating microtubules
what are centrioles?
a pair of rod like structures involved in cell division
what are microfilaments?
- give form and shape to the cell
- form flagella
- help form cilia
what is the cilia?
slender, microscopic hair like structures that extend from the surface of most mammalian cell
what is the flagella?
microscopic hairs that are involved in locomotion of cells
what are chromosomes?
- DNA and RNA molecules
- matching pairs are homologous pairs
how many homologous pairs do dogs, cats, rabbits, and guinea pigs have?
dogs - 78
cats - 38
rabbits - 44
guinea pigs - 64
what are autosomes?
non-sex chromosomes
what are allosomes?
sex chromosomes
which is smaller out of the X and Y chromosome?
Y
how is a chromosome made?
made up of 2 identical chromatids held together at the centomere
what are the DNA pairs?
adenine + thymine
cytosine + guanine
what are uprights?
chains of alternating sugar and phosphate units
what are rungs?
formed from pairs of base attached to the sugars
what are the two types of cell division?
- mitosis
- meiosis
when and where does mitosis occur?
continuously in growing and adult animals
how many cells does the nucleus split into during mitosis?
2 identical daughter cells
what is the process called when the cytoplasm divides?
cytokinesis
what ae the 5 phases of mitosis?
1 - prophase
2 - metaphase
3 - anaphase
4 - telophase
5 - interphase
mitosis: what happens during prophase?
- chromosomes coil up
- nuclear envelope breaks down
- ends when fully broken down
mitosis: what happens during metaphase?
- chromosomes line up in centre of cell
- spindle fibres connect to kinetochores
mitosis: what happens during anaphase?
- spindle fibres contract and pull the chromatids
- when they split = daughter chromosomes
- ends when chromosomes reach their destination
mitosis: what happens during telophase?
- nuclear membrane and nucleolus reform in daughter cells
-spindle cell fibres degenerate - chromatids uncoil and lengthen
mitosis: what happens during interphase?
period of rest - intense metabolic activity
where does meiosis take place?
in gametes (ova/sperm)
how many daughter cells does meiosis create?
4 daughter cells
what is it called when two gametes join together?
zygote
meiosis 1 : what happens during prophase 1?
- chromosomes thicken and coil up
- nuclear envelope breaks down
- chiasmata (crossover) happens
meiosis 1: what happens during metaphase 1?
- chromosomes line up along centre in pairs
-spindle fibres connect to kinetochores
meiosis 1: what happens during anaphase 1?
- spindle fibres contract and pull the chromosomes at the centromere
- one chromosome pair pulled to each line
- anaphase ends when chromosomes reach their destination
meiosis 1: what happens during telophase 1?
- nuclear membrane and nucleolus reformed in daughter cells
- spindle fibres disappear
- cytoplasm and cell divides resulting in two cells with a haploid set of paired chromosomes
what happens in meiosis 2?
- 2 daughter cells divide again
- 4 cells make up the gametes
meiosis 2 : what happens during prophase?
- centrioles start moving to opposite poles again
- happens in each daughter cell
meiosis 2: what happens during metaphase?
- chromosomes line up in single file
- spindle fibres attach
meiosis 2: what happens during anaphase?
- sister chromatids are pulled to opposite poles of the equator
meiosis 2: what happens during telophase?
- spindles break down
- new nuclear membranes form and new nucleoi form around the 2 groups of chromatids
- chromatids uncoil and lengthen
