Chapter 1 - Cell Biology Flashcards
What subcellular structures do all eukaryotic (plant and animal) cells contain?
Cell membrane, cytoplasm, and genetic material enclosed in a nucleus.
What subcellular structures do prokaryotic cells (bacterial cells) contain?
Cytoplasm and a cell membrane surrounded by a cell wall. Single DNA loop.
Nucleus function
Contains genetic material that controls the activities of the cell.
Cell membrane function
holds the cell together and controls what goes in and out
mitochondria function
where most reactions for aerobic respiration take place
chloroplasts function
where photosynthesis occurs - contains chlorophyll which absorbs the light needed
plasmids function
replicate and move between cells so that genetic information can be shared - plasmids are small rings of DNA
what subcellular structures do most animal cells contain
nucleus, cytoplasm, a cell membrane, mitochondria, ribosomes
what subcellular structures do plant cells commonly have
chloroplasts and a permanent vacuole filled with cell sap
what does the cell wall contain
cellulose, which strengthens the cell (plant and algal cells only)
how are sperm cells specialised for reproduction
- long tail and streamlined head to help it to swim to the egg
- many mitochondria to provide the energy needed
- carries enzymes in its head to digest through the egg cell membrane
how are nerve cells specialised for rapid signalling?
nerve cells carry electrical signals from one part of the body to another
- long cells
- branched connections at their ends to connect to other nerve cells and form a network throughout the body
how are muscle cells specialised for contraction?
- long cells (so they have space to contract)
- many mitochondria to generate the energy needed for contraction
how are root hair cells specialised for absorbing water and minerals?
- large surface area as they have long ‘hairs’ which stick out of the soil
how are phloem and xylem cells specialised for transporting substances?
- phloem and xylem cells form phloem and xylem tubes, which transport substances such as food and water around plants.
- xylem cells are hollow in the centre and phloem cells have very few subcellular structures, so that substances can flow through them
what is cell differentiation?
a cell changes to become specialised for its job
when do plant and animal cells differentiate?
animal - at an early stage
plant - retain the ability to differentiate throughout life
why can we see more with an electron microscope than with a light microscope?
higher magnification and resolving power
formula for magnification
size of image / size of real object
how do bacteria multiply
via simple cell division (binary fission) could be as often as 20min if provided with enough nutrients and a suitable temperature
what are chromosomes
found in the nucleus and are made of DNA molecules and each chromosome carries a large number of genes - normally found in pairs in body cells.
describe the steps of the cell cycle
- genetic material is doubled then divided into two identical cells
- before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome
- MITOSIS - one set of chromosomes is pulled to each end of the cell and the nucleus divides
- the cytoplasm and cell membranes divide to form two identical cells
describe binary fission
- dna and plasmid replicate
- cell gets bigger and the dna strands move to opposite ‘poles’ (ends) of the cell
- cytoplasm begins to divide and new cell wall begins to form
- cytoplasm divides and two daughter cells are produced. each daughter cell has one copy of the dna.
whats a stem cell?
an undifferentiated cell of an organism, which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation
diffusion definition
the spreading out of particles from an area of higher concentration to an area of lower concentration
factors that affect the rate of diffusion
- difference in concentration
- temperature
- surface area of the membrane
osmosis meaning
is the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
in a larger organism is the sa:v bigger or smaller?
smaller
what is active transport?
movement of substances from a lower to a higher concentration against a concentration gradient
