Cells Flashcards
what do cells do?
takes nutrients
expel waste
grow and repair themselves
Nucleus
brain of the cell
contains chromosomes
What does chromosomes do?
they contain DNA and this tells the cell how to function. it carries instructions on how to behave and information for protein synthesis
what chemical is the nucleus made up of and what does it produce?
it is made up of RNA (Ribonucleic Acid).
The nucleolus also produces ribosomes used in protein synthesis
cell membrane
also known as the plasma membrane
covered with carbs and these are believed to help the cell recognise other cells.
What is diffusion
particles moving from an area of high concentration > low concentration particles “spreading out”
Simple diffusion
Oxygen and water enter the cell in this way.
Molecules that are soluble in lipids will passively dissolve in the lipid part of the cell membrane and diffuse across it.
Facilitated diffusion
A type of passive diffusion, this is where the substance attaches to a carrier protein to help it cross the cell membrane. this occurs through pores in the cell membrane - these are pores along the membrane that allow small molecules to pass through
Active transport
this form of transport requires a carrier and requires energy to enter the cell as it is moving against the concentration gradient. the energy of the carrier cell(ATP) is used. sodium enters the cell in this way
endocytosis and exocytosis and phagocytosis
cells can ingest materials by engulfing them
endocytosis - engulfed in membrane - particles enter the cell
exocytosis - particles expelled from the cell
phagocytosis - without membrane
what is cytoplasm
fluid that fills inside of the cell. this provides the cell with support
contains glucose, protiens and ions
what is the mitochondria
responsible for cellular respiration
energy extraction from food and the energy is stored as ATP
Lysosomes
they digest material taken in by the cell during phagocytosis and endocytosis
ribosomes
protein synthesis
float freely in the cytoplasm and attach themselves to the endoplasmic reticulum
rough endoplasmic reticulum
transports and adds structure to proteins that have been synthesised by ribosomes
Golgi body
modification of proteins for their final destination
helps in the formation of lysosomes
smooth endoplasmic reticulum
synthesis and transport of lipids and steroids
organelles peroxisomes
bound by a single membrane and they contain enzymes
active process of detoxification
Vacuole
they are filled with cell sap or food
particles, air or water/fluid
its function is to maintain pressure within a plant cell
hold waste and other material
Flagella
an extension of the cell membrane on certain cells to allow propelling moving for example spermatozoa
Cilia
an extension of the cell membrane and allow smaller wavelike movements over the cell surface to move debris and fluid
chromosomes
thread like structure of nucleic acids and protein found in the nucleus, carrying genetic information in the form of genes
Chromatid
each of the two thread like strands into which a chromosome divides during cell division
Centromere
the point on a chromosome by which it is attached
diploid number
2 sets of chromosomes (full set)
haploid number
single set of unpaired chromosomes (half)
centrosomes/ centrioles
organelle near the nucleus of cell which contains the centrioles which form the spindle fibres for cell division
what chromosomes do cats and dogs do
dogs 39 pairs 78 in total
cats 19 pairs 38 in total
cell division (somatic cells)
divide by mitosis these are the body cells apart from reproductive cells. these cells contain the diploid number of chromosomes
cell division ( germ cells)
divide by meiosis. These cells are sex cells. sperm and ova and these contain the haploid number of chromosomes
Mitosis
somatic cells replicate by binary fission meaning dividing into 2
mitosis - prophase
- chromosomes already replicated
- nuclear membrane breaks down
-chromosomes contract and shorter/fatter - centrioles are now at each end of the cell
mitosis - metaphase
- chromosomes line up on the equator
-chromatids draw apart at the centromere
Mitosis - Anaphase
- chromosomes attach themselves to spindle fibres
- chromatids move apart to opposite poles of the cell
mitosis - telophase
- chromatids will be the new chromosomes for the daughter cells
- spindle fibres break down
- nuclear membrane reforms itself
- cell constricts in the middle until it divides into 2
Mitosis - interphase
this phase is classed as rest phase, it is often considered as the first, or the last phase
DNa makes a copy of itself ready for the prophase
meiosis prophase 1
starts with diploid no. of chromosomes
identical chromosomes lie side by side and duplicate
crossing over occurs here resulting in new combinations of genes
meiosis metapahse 1
homologous pairs of chromosomes line at the equator of the cell
fibrous spindle starts to form
chromosomes arrange in pairs
meiosis - anaphase
pairs seperate into chromatids migrate along the spindle fibres towards the end of the cell
meiosis - telephase
cytoplasm starts to divide
the nuclear membrane doesn’t reform
we now have two daughter cells
prophase 2 meiosis
transitionary phase - no replication
metaphase 2
chromosomes line up in the centre of the cell and attach to the spindle apparatus
meiosis - anaphase
the spindle fibres contract pulling the chromatids and apart at the centromere, so that they move to opposite ends of the cell
telophase 2 - meiosis
the cutoplasm divides and the nuclear membrane reforms
mitosis vs meiosis
mitosis
-somatic cells
- diploid (full) no chromosomes
-2 daughter cells
Meiosis
- sex/germ cells
- haploid (half) no chromosomes
- 4 daughter cells
