Topic 3 - Voice Of The Genome Flashcards
What are the 10 organelles in an animal cell?
- Cell membrane
- Rough er
- Smooth er
- Lysosomes
- Centrioles
- Nucleus
- Nucleolus
- 80s ribosomes
- Golgi
10.mitochondrion
What do the ReR and SeR do?
- Covered in ribosomes, involved in protein trafficking and is membrane bound.
- Does lipid synthesis,it makes new membrane
What does the mitochondrion do?
It is involved in aerobic respiration, has circular DNA chromosomes, outer membrane is smooth and inner membrane is folded into cristae. Also contains 70S ribosomes.
What does the Golgi do?
Is a series of flattened membrane vesicles, it sorts and modifies proteins.
What do lysosomes and centrioles do?
- Membrane bound vesicles that contain digestive enzymes
- Hollow cylinders made of microtubules that sit at right angles and organise fibres during cell division.
What does the nucleus and nucleolus do?
- MRNA leaves out of its pores.
- Transcription takes place there.
What are the 80s ribosomes for?
Protein synthesis
What are the 9 organelles that make up prokaryotic cells?
- Pili = not in all bacteria, allow plasmids to be passed between bacteria
- Slime capsule = protects from dehydration
- Cell wall = made up of peptidoglycans (sugars and amino acids)
- Cell membrane
- Mesosome = infolding of cell membrane, existence is controversial
- Flagellum = not in all bacteria, rotates for movement
- Nucleoid = bacterial chromosomes, circular molecule of DNA, DNA is not wrapped around proteins
- Plasmids = small circles of DNA, contains extra genes.
- 70S ribosomes = for translation, smaller than Eukaryotic ones
What are 2 similarities between prokaryotic and eukaryotic cells?
- Both have organelles
- Both cell membranes are made up of phospholipid bilayer which controls passage of substances across exchange surfaces.
What are 4 differences between eukaryotic and prokaryotic cells?
- Prokaryotic cells make up single celled organisms whereas eukaryotic cells make up complex organisms.
- Eukaryotic cells are larger and more complex whereas prokaryotic cells are smaller (0.1-5 micrometres)
- Eukaryotic cells contain membrane bound structures whereas prokaryotic dont.
- Prokaryotic cells use binary fission whereas eukaryotic cells use mitosis and meiosis.
What are the 4 components of the sperm cell?
- Flagellum = rotates so sperm can swim to egg
- Mitochondria= spiral shaped to provide energy for flagellum
- Haploid nucleus
- Acrosome = modified lysosome, contains digestive enzymes to digest zona pollucida
What are the 6 components of an ovum?
- Follicle cells from ovary = release chemicals to attract sperm
- Zona pollucida = jelly like layer around egg
- Cell membrane
4.lysosomes = around the edge and contain enzymes which harden zona pollucida following fertilisation. - Lipid droplets = provide nutrients to zygote
- Haploid nucleus
What are 3 adaptations of the ovum?
- Egg is much larger than sperm as it contains nutrients and so sperm can find it easily.
- Follicle cells attract sperm and provide protective coating
- Jelly like glycoprotein layer, zona pollucida, forms in-penetrable barrier after fertilisation.
What are the 8 steps of fertilisation?
1.sperm cells attracted to ovum by the chemicals released from the follicle cells.
2. Sperm cell attaches to follicle cells and chemicals from follicle cells trigger the acrosome reaction.
3. Acrosome swells and fuses with sperm cell membrane.
4. Enzymes released from acrosome digest through follicle cells and zona pollucida.
5. Sperm cell fuses with ovum cell membrane
6. Sperm nucleus enters ovum
7. Cortical reaction takes place where enzymes are released from lysosomes which harden the zona pollucida to prevent further fertilisation.
8. Sperm and ovum nuclei fuse.
What are the 6 steps of protein trafficking?
- DNA is transcribed into mRNA, the mRNA leaves nucleus through the nuclear pore.
- MRNA binds to a ribosome on the Rough er and is translated into the lumen of the er.
- Polypeptide chain is folded into a protein and packaged into a vesicle
4.vesicle buds off er and fuses with Golgi. - Proteins are modified by adding carbs and sorted by destination.
- Vesicle buds off Golgi and fuses with cell membrane and released outside of the cell.
Which type of cell division produces gametes?
Meiosis
What is meiosis?
Type of cell division that produces gametes with a haploid number of chromosomes.
What are the 3 steps of meiosis?
- DNA replication, each chromosome is replicated.
- Meiosis 1, where the homologous chromosomes line up and divide into 2 daughter cells each with only one homologous pair.
- Meiosis 2, where the 2 divide into 4 haploid daughter cells, each with only one chromatid from each homologous pair.
How do you work out the number of all the possible chromosome combinations?
2^n n= number of pairs of chromosomes.
How does meiosis provide genetic variation?
By crossover/recombination and independent assortment.
What is crossover?
It takes place in meiosis 1.
Homologous chromosomes line up and have points where they are in contact which are called chiasmata. Where the chiasmata are, the chromatids break off and switch places.
Definition of locus?
Location of a gene on a chromosome
What does linkage refer to?
Linkage refers to how alleles of genes on the same chromosome are more likely to be in the same gamete after meiosis so are inherited together.
Why do 2 genes that are more linked have a higher chance of being inherited together?
This is because the closer the loci of two genes on a chromosome, the less likely a crossover will occur between them so they are more linked.
What is independent assortment?
It is a random process where either chromosome from each pair could end up in any gamete as it depends on which side the chromosome is.
What is sex linkage?
Genes that are only on the x or Y chromosomes.
Why are recessive genes on X chromosome more likely to exhibit their phenotype in males?
Because there is no other allele on the Y chromosome to dominate it.
