topic 1 Flashcards
(26 cards)
What are cells ?
Cells are the building blocks of life as all living things are made of cells.
What are prokaryotes ?
Prokaryotes are prokaryotic cells which are smaller and simpler than eukaryotes. an example of a porkaryote is a bacterial cell.
What are eukaryotes ?
Eukaryotes are organisms made up of euaryotic cells which are complex and include plant and animal cells
What are the features of an animal cell?
> Nucleus - contains genetic material and controls cell activity
Cytoplasm - where most chemical reactions take place (contain enzymes to control chemical reactions)
Cell membrane - holds cell together and controls what goes in and out
Mitochondria - where reactions for respiration take place (respiration transfers energy that cell needs to work)
Ribosomes - where proteins are made
What are the features of a plant cell ?
> Cell wall - made of cellulose and strengthens cell
Permanent vacuole - contains cell sap (weak solution of sugar and salts
Chloroplasts -where photosynthesis takes place(makes food for plant), contain chlorophyll (absorbs light for photosynthesis)
ALSO CONTAIN ALL OF ANIMAL CELL FEATURES
What are the features of a bacterial cell ?
> Cell wall
Cell membrane
Cytoplasm
DNA - single circular strand that floats freely i cytoplasm
Plasmids - small rings of DNA (may contain one or more)
What do microscopes do ?
They allow us to see things we cant see with the naked eye.
what are light microscopes ?
They are microscopes which use light and lenses to form an image and magnify. They let us see individual cells and large subcellular structure like nuclei.
What are electron microscopes ?
They are microscopes which use electrons to form an image. They have a higher magnification and a higher resolution(gives a sharper image). These let us see smaller things in more detail.
What is the formula for magnification ?
magnification = image size/real size
What is cell differentiation ?
The process by cells change to become specialised. When cells change, they develop different structures and turn into different cells. This allows them to carry out specific functions. undifferentiated cells are called stem cells.
How is a sperm cell adapted for its job ? (reproduction)
> Has a long tail and streamlined head to help when swimming
Has lots of mitochondria for energy
Contains enzymes in head to digest through egg cell membrane
How are nerve cells adapted for their job ? (rapid signalling)
> Long to cover more distance
>Branched connections to connect to other nerve cells and form a network
How are muscle cells adapted for their job ? (contraction)
> Long for space to contract
>Contain lots of mitochondria for energy to contract
How are root hair cells adapted for their job ? (absorbing water and minerals)
> They have long hairs that stick out into the soil giving the plant a larger surface area for absorbing water and mineral ions from the soil.
How are phloem and xylem cells adapted for their job ? (transporting substances)
> They are long and join end to end
>Xylem are hollow and Phloem have little subcellular structures to allow stuff to flow through
What are chromosomes ?
Coiled up lengths of DNA molecules which control the development of different characteristics. Each chromosome carries a large number of genes. Body cells usually have 2 copies of each chromosome - one from the mother and one from the father - there are 23 pairs of chromosomes
What is the cell cycle ?
Where body cell in multicellular organisms divide to produce new cells. Mitosis is the part where the cell divides. Multicellular organisms use mitosis to grow or replace cells that have been damaged. the end of the cycle is where 2 new cells identical to the original with the same number of chromosomes is made.
What are the 2 main stages of the cell cycle ?
> Growth & DNA replication
>Mitosis
Explain the process of growth and DNA replication
- In a cell that is not dividing, the DNA is all spread out in long strings.
- Before it divides, the cell has to grow and increase the amount of subcellular structures (mitochondria and ribosomes)
- It then duplicates its DNA - one copy for each new cell. The DNA s copied and forms x-shaped chromosomes. Each ‘arm’ of the chromosome is the exact copy of the other.
Explain the process of Mitosis
- Chromosome line up at centre of cell, cell fibres pull them apart. 2 arms of each chromosome go to opposite ends of the cell
- Membranes from around sets chromosome - become nuclei of 2 new cells - the nucleus has divided
- Cytoplasm and cell membrane divide - cell has produced 2 new daughter cells (contain exactly same DNA (identical) DNA is also identical to parent cell)
What is binary fission ?
(Prokaryotic cells replicate by binary fission)(cell splits in two)
- The circular DNA and plasmids replicate
- Cell gets bigger and circular DNA strands move to opposite eds of the cell.
- Cytoplasm begins to divide and new cell walls form
- Cytoplasm divides and 2 daughter cells are produced - each daughter cell has one copy of DNA strand but has a variable number of plasmids
What are the right conditions for bacteria to divide ?
> A warm environment and lots of nutrients
if conditions become unfavorable, cells stop dividing and eventually begin to die
What is diffusion ?
The process of particles moving from an area of a high concentration to a low concentration. This takes place in both solutions and gases. The
