cells Flashcards
1
Q
bacterial cells
A
- cell wall, made from peptidoglycan (a mixture of proteins, lipids and sugars)
- cell membrane
- cytoplasm
- nucleoid/chromosomal DNA, large ring of DNA containing genetic material, it is free-floating (no membrane)
- plasmids, small ring of double-stranded circular DNA
- flagellum, tail like structure used for movement, not found on all bacterial cells
- ribosomes
2
Q
cytoplasm contains…
A
- dissolved salt ions and sugar molecules
- fat molecules, enzymes, amino acids
- food reserves: glycogen in animal cells, starch in plant cells
- organelles
3
Q
organelles with double membranes
A
- nucleus
- mitochondria
- chloroplast
4
Q
cell wall
A
- plants only
- made of cellulose
- freely permeable to water and salts
5
Q
chloroplasts location
A
only present in photosynthetic plant cells eg. not in root hair cells
6
Q
plasmids
A
- carries genetic information for specialist cell functions (like antibiotic resistance)
- can replicate and operate independently from the chromosomal DNA
- can be readily moved between different bacterial cells, including for genetic engineering (biotechnology) purposes.
7
Q
difference between eukaryotic and prokaryotic DNA
A
- DNA in eukaryotic cells are in the nucleus, prokaryotic cells have DNA but no nucleus
- eukaryotic cells usually contain several large chromosomes, but a prokaryotic cell usually only contains one per cell
- DNA in prokaryotic cells are circular with no free ends, but the DNA of eukaryotic cells forms large linear chromosomes with free ends
8
Q
factors affecting diffusion rate
A
- conc gradient: the greater the difference in concentration of particles, the faster the rate of diffusion
- temperature: higher temp, higher diffusion rates
- distance: the further the particles have to travel, the longer diffusion takes
- size: the smaller the particles, the faster they can diffuse.
- surface area: the larger the surface area, the faster the molecules will diffuse.
9
Q
roles of mitosis
A
- allows organisms to grow in size by increasing their total number of cells
- allows worn-out and dead cells to be replaced -> tissue repair
- allows some species to reproduce by asexual reproduction
10
Q
mitosis and cancer
A
- if errors are detected in a cell, such as a mutation in the DNA that cannot be repaired, the cell will be destroyed
- if a cell with errors is not destroyed, the cell cycle will continue and the cell will divide by mitosis
- this may lead to a group of cells that are defective and divide uncontrollably, which can form a tumour -> cancer
11
Q
meiosis
A
- called reduction division because the chromosome number is halved from diploid 46 to haploid 23
- used for gamete formation
- happens in reproductive organs (testes & ovaries)
- 4 haploid cells are produced from 1 diploid cell
- daughter cells are genetically different to parent cells and to each other
- has an interphase stage
12
Q
meiosis steps
A
- parent diploid cell has 46 chromosomes, 46 chromatids
- chromosomes make identical copies of themselves: 46 chromosomes, 92 chromatids
- homologous chromosomes pair up
- sections of DNA get swapped (crossing over)
- cell divides once, producing 2 haploid cells with 23 chromosomes, 46 chromatids
- haploid cells further divide, giving 4 haploid daughter cells with 23 chromosomes, 23 chromatids
13
Q
binary fission
A
- the process by which asexual reproduction happens in bacteria
- a single organism becomes two independent organisms
- binary fission also describes the duplication of organelles in eukaryotes (eg. mitochondria)
14
Q
binary fission steps
A
- DNA is replicated within the cell
- DNA is separated into alternate ends of the single cell
- the plasma membrane pinches the cell apart, and one cell becomes two
- they become independent organisms
- daughter cells are genetically identical if no mutations occur in the DNA when copied
15
Q
The offspring in sexual reproduction are genetically different to…
A
- their parents because they receive half of their genetic information from each parent in the gametes
- each other because the gametes produced by meiosis are genetically different from each other and it is completely random which of the gametes from each parent will then fuse at fertilisation to form the zygote.
