Section 2 Cells Flashcards
What are the 5 kingdoms in biology
Animal, plant, bacteria, fungi and protoctista
Eukaryotic and prokaryotic cells
Eukaryotic= Animal/plant cell with membrane bound organelles
Prokaryotic= Bacteria has no membrane bound organelles
What are the 2 forms of sexual reproduction?
Sexual and asexual
Sexual= In animals and in some plants 2 parents to produce a zygote which develops into an organism.
Asexual= 1 parent to produce genetically identical offspring
How does a zygote develop into an organism?
Zygote is a stem cell
Stem cells are undifferentiated or unspecialised and can form any type of cell.
Zygote divides by mitosis to make many stem cells
These copy to form tissues then organs then organ systems which is then surrounded by a body.
Define tissue, organ and organ system
Tissue= is a group of specialised cells
Organ= Formation of tissue
Organ system= organs working together for a bodily function
What is an animal cell made of?
Organelles (nucleus, endoplasmic reticulum, golgi body, lysosomes, mitochondria, ribosomes) – all have membrane except the ribosomes
Cytoplasm (site of chemical reaction)
Cell Membrane (holds cell contents together, controls what enters/leaves cell, cell signalling)
Structure of a nucleus
contains DNA (made of genes, genes code for making proteins)
DNA wrapped around histones to form Chromatin
nucleus has a double membrane, called Nuclear Envelope, which contains pores
at centre of nucleus is Nucleolus – produces mRNA (copy of a gene)
rest of nucleus made of Nucleoplasm (contains the DNA/chromatin)
Endoplasmic reticulum
2 types
Rough and smooth
Rough= Has ribosomes on and makes proteins
Smooth= Has no ribosomes and makes lipids and carbohydrates
Golgi body
Modifies and packages proteins
Packs them into vesicles for transport
Mitochondria
Site of respiration (produces ATP) power house of the cell
Has a double membrane
Middle portion called matrix
Ribosomes
Ribosomes attached to rough endoplasmic reticulum and is the site of protein synthesis.
Plant cells
Organelles (nucleus, endoplasmic reticulum, golgi body, lysosomes, mitochondria, chloroplast, vacuole, ribosomes) – all have membrane except the ribosomes
Cytoplasm (site of chemical reaction)
Cell Membrane (holds cell contents together, controls what enters/leaves cell, cell signalling)
Cell Wall (made of cellulose, prevents cell from bursting or shrinking)
Structure of chloroplasts
The plant cells site of photosynthesis
Has a double membrane
Contains discs called thykaloids which contain chlorophyll
These stacked are called granum
This then surrounded by a fluid called stroma
What is vacuole?
Surrounded by a membrane called a tonoplast, contains Cell sap
What is bacteria made of?
No nucleus- loose DNA in the form of a single loop and plasmid
No membrane bound organelles: smaller ribosomes, mesosomes infolding of cell membrane for respiration.
Cytoplasm
Cell membrane cell wall
What are viruses made of?
DNA or RNA
Protein coat called caspid and lipid coat
Chromosome
DNA in coiled form
Formed during interphase of cell division
Made of 2 identical sister chromatids joined at the centre by a centromere
Carries 2 copies of the same DNA molecule
What is homologous pair of chromosomes?
A pair of chromosomes, 1 maternal and 1 paternal
Carries the same genes but different alleles
What is cell division?
Formulation of new cells in multi cellular organisms
2 methods= produces genetically identical
Mitosis produces genetically identical cells for growth and repair of tissues
Meiosis produces genetically different haploid cells as gametes for sexual reproduction (haploid meaning half the genetic information).
What does Mitosis (cell cycle) produce?
2 genetically identical cells, diploid (have full set of chromosomes/DNA)
What are the benefits of mitosis?
Growth and repair of tissues
Stages of mitosis
IPMATc
Interphase, prophase, metaphase, anaphase, telophase and cytokenisis (splitting)
What happens during the different stages of mitosis?
Interphase:
G1: protein synthesis
S: DNA replication (doubles set of DNA)
G2: organelle synthesis
Prophase: DNA coils to form chromosomes, nucleus breaksdown, spindle fibres form
Metaphase: chromosomes line up in middle of cell and attach to spindle fibre via centromere
Anaphase: spindle fibres pull, centromere splits, sister chromatids move to opposite sides
Telophase: chromatids uncoil, nucleus reforms (left with 2 genetically identical nuclei)
Cytokiensis: Separating cell into into 2
What happens to DNA mass in mitosis?
Halves
What happens to the chromosome number in mitosis?
Stays the same (diploid).
What is Cancer?
formation of a tumour due to uncontrolled cell division (uncontrolled mitosis)
How does uncontrolled cell division occur?
due to mutation of DNA/cells forming cancer cells
mutation can occur randomly or due to mutagens (chemicals/radiation)
cancer cells are rapidly dividing cells (like hair cells, skin cells, red blood cells), they spend less time in interphase and more time in the other stages (mitosis)
Treatment for Cancer?
Surgery = aim is to remove tumour
Chemotherapy = - using drugs that inhibit mitosis in rapidly dividing cancer cells
- problem, also affect normal healthy cells (hair cell, skin cells, rbcs) causing side effects (hair loss, dry skin, tiredness)
- treatment given as regular doses to allow time for normal healthy cells to recover in number
Radiotherapy = radiation used to destroy cancer cells
What does meiosis produce ?
4 genetically different cells with half the amount of genetic information (haploid).
Benefits of meiosis?
Allows for variation within species by producing gametes with different alleles but the same genes.
Stages of meiosis?
Interphase, meiosis 1, meiosis 2, cytokinesis
Interphase of meiosis?
Interphase? G1: protein synthesis
S: DNA replication (doubles set of DNA)
G2: organelle synthesis
Meiosis 1 process
Prophase I: DNA coils to form chromosomes, nucleus breaksdown, spindle fibres form, crossing over occurs
Metaphase I: homologous pair of chromosomes line up in middle of cell and attach to spindle fibre via centromere by random assortment
Anaphase I: spindle fibres pull, homologous pair of chromosomes separate to opposite sides by independent segregation
Telophase I: chromosomes uncoil, nucleus reforms (left with 2 nuclei)
Meiosis 2 process
Prophase II: DNA coils to form chromosomes, nucleus breaksdown, spindle fibres form
Metaphase II: chromosomes line up in middle of cell and attach to spindle fibre via centromere by random assortment
Anaphase II: spindle fibres pull, centromere splits, sister chromatids move to opposite sides by independent segregation
Telophase II: chromatids uncoil, nucleus reforms (left with 4 genetically different nuclei)
Cytokinesis of meiosis
separating cell into 4 (each receives a nucleus and organelles/cytoplasm)
How does Meiosis produce Variation?
Crossing Over and Independent Segregation